Table of Contents
Glossary of TypeScript Programming Language Terms
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TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. It adds static typing to JavaScript, helping developers catch type-related errors during development rather than runtime. TypeScript enhances code maintainability and scalability, especially in large applications. https://www.typescriptlang.org/
Interface in TypeScript defines a contract for the shape of an object, specifying the types of properties it should have. Interfaces help enforce structure in objects and enable better code readability by clearly defining the expected object format. https://www.typescriptlang.org/docs/handbook/interfaces.html
Type in TypeScript is a way to declare a specific shape for a variable or parameter. Type annotations help provide clarity and catch type-related errors early. The type keyword can also be used to create more complex types by combining multiple types together. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html
Union Types in TypeScript allow a value to be one of several specified types. For instance, `string | number` means a variable can hold either a string or a number. Union Types are useful for handling multiple types in a function or variable. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#union-types
Generics in TypeScript allow for the creation of reusable components that can work with a variety of types instead of a single one. Generics enhance code flexibility while maintaining type safety, especially in functions, classes, and interfaces. https://www.typescriptlang.org/docs/handbook/2/generics.html
Enum in TypeScript is a data type that allows developers to define a set of named constants. Enums provide a way to work with a collection of related values, making code more readable and maintainable, especially when handling fixed sets of options. https://www.typescriptlang.org/docs/handbook/enums.html
Modules in TypeScript are mechanisms to organize and encapsulate code, making it easier to manage and scale large applications. Modules can export classes, functions, and variables, which can then be imported and used in other files. https://www.typescriptlang.org/docs/handbook/modules.html
Decorators in TypeScript are special declarations that can be attached to classes, methods, or properties to modify their behavior. Decorators are a form of meta-programming and are commonly used in frameworks like Angular to handle tasks like dependency injection. https://www.typescriptlang.org/docs/handbook/decorators.html
Ambient Declarations in TypeScript are used to describe the shape of libraries or frameworks that TypeScript doesn’t know about. These declarations allow developers to use external JavaScript libraries with type information by defining them in a `.d.ts` file. https://www.typescriptlang.org/docs/handbook/declaration-files/introduction.html
Strict Mode in TypeScript is a compilation mode that enforces stricter type checking and better safety guarantees. Strict Mode helps developers catch more errors early by imposing rules like requiring all variables to be explicitly typed and ensuring that all null values are handled properly. https://www.typescriptlang.org/tsconfig#strict
Type Inference in TypeScript is a feature where the compiler automatically determines the type of a variable based on its assigned value. Type Inference reduces the need for explicit type annotations while maintaining type safety, especially in cases where types are obvious. https://www.typescriptlang.org/docs/handbook/type-inference.html
Type Assertion in TypeScript is a way to explicitly tell the compiler the type of a variable, overriding its inferred type. Type Assertion is useful when the developer has more knowledge about the variable than the compiler, such as when interacting with DOM elements. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#type-assertions
Intersection Types in TypeScript combine multiple types into one. A value with an Intersection Type must satisfy all the combined types, making it useful for composing different type definitions and ensuring a value adheres to multiple structures. https://www.typescriptlang.org/docs/handbook/2/objects.html#intersection-types
Mapped Types in TypeScript allow you to create new types by transforming properties in an existing type. Mapped Types are useful for making complex transformations on types, such as marking all properties as optional or readonly. https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Readonly in TypeScript is a keyword that makes properties of an object immutable, preventing their values from being modified after initial assignment. Readonly is useful for ensuring that certain data remains unchanged throughout the lifecycle of an application. https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytype
Partial in TypeScript is a utility type that makes all properties of an object optional. Partial is useful when you want to update or modify only some properties of an object without needing to provide all of them. https://www.typescriptlang.org/docs/handbook/utility-types.html#partialtype
Pick in TypeScript is a utility type that creates a new type by selecting a subset of properties from an existing type. Pick is useful when you need to work with only specific parts of an object while preserving the type structure. https://www.typescriptlang.org/docs/handbook/utility-types.html#picktype-keys
Omit in TypeScript is a utility type that constructs a new type by excluding certain properties from an existing type. Omit is useful for creating variations of types without specific fields that aren’t needed for a particular operation. https://www.typescriptlang.org/docs/handbook/utility-types.html#omittype-keys
Never in TypeScript is a type that represents values that will never occur. Never is used primarily in functions that never return, such as those that throw errors or have infinite loops, helping indicate unreachable code. https://www.typescriptlang.org/docs/handbook/basic-types.html#never
Void in TypeScript is a type that represents the absence of a value, commonly used as the return type for functions that do not return anything. Void is useful for distinguishing functions that produce side effects from those that return meaningful results. https://www.typescriptlang.org/docs/handbook/basic-types.html#void
Tuple in TypeScript is a type that allows an array with fixed sizes and types for each element. Tuple is useful for scenarios where the array elements are of different types and have a specific order, such as returning multiple values from a function. https://www.typescriptlang.org/docs/handbook/2/objects.html#tuple-types
Unknown in TypeScript is a type that represents any value, similar to any, but it is safer because the compiler forces you to perform type checks before operating on values of type Unknown. Unknown is useful when dealing with data from dynamic sources, ensuring type safety before proceeding. https://www.typescriptlang.org/docs/handbook/2/functions.html#unknown
Conditional Types in TypeScript are types that are based on a condition expressed with `extends`. They allow for more flexible and dynamic types depending on other types. Conditional Types are useful for transforming or narrowing types based on certain conditions. https://www.typescriptlang.org/docs/handbook/2/conditional-types.html
Discriminated Unions in TypeScript are a way to combine Union Types with a shared property, usually a literal type, to safely narrow down the union into more specific types. Discriminated Unions are useful for handling multiple types in a type-safe way, especially in state machines or APIs. https://www.typescriptlang.org/docs/handbook/2/narrowing.html#discriminated-unions
Optional Chaining in TypeScript is a feature that allows you to safely access deeply nested properties in an object without causing runtime errors if a property is `undefined` or `null`. Optional Chaining is useful for working with data that may not be fully populated. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#optional-chaining
Nullish Coalescing in TypeScript is a feature that allows you to provide a default value for `null` or `undefined` expressions. Using `??`, Nullish Coalescing ensures that only `null` or `undefined` trigger the default value, and not falsy values like `0` or `false`. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#nullish-coalescing
Keyof in TypeScript is an operator that takes an object type and returns a union of its keys. Keyof is useful for creating types that depend on the keys of an object, especially when working with dynamic object structures. https://www.typescriptlang.org/docs/handbook/2/keyof-types.html
Indexed Access Types in TypeScript allow you to access the type of a specific property in an object type. Indexed Access Types are useful when you want to dynamically look up property types and maintain type safety. https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
Type Guards in TypeScript are methods or expressions that allow you to narrow down the type of a value inside a conditional block. Type Guards are useful for ensuring that your code operates on values of a specific type within certain code paths. https://www.typescriptlang.org/docs/handbook/2/narrowing.html
Literal Types in TypeScript allow you to specify exact values as types, such as specific strings or numbers. Literal Types are useful when you want to limit a variable to a set of specific values, such as status codes or commands. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-types
Mapped Types in TypeScript are a way to create new types by transforming each property in an existing type using a mapping operation. Mapped Types are useful for applying changes like making properties optional, readonly, or removing certain properties. https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Template Literal Types in TypeScript allow you to create types by combining string literal types with embedded expressions. Template Literal Types are useful for constructing complex string types dynamically, such as combining prefixes and suffixes. https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
Type Narrowing in TypeScript is the process of refining a variable from a broad type to a more specific type using control flow or type guards. Type Narrowing is useful for ensuring that variables are safely used within their proper type constraints in different branches of code. https://www.typescriptlang.org/docs/handbook/2/narrowing.html
Recursive Types in TypeScript allow types to refer to themselves, enabling you to create complex types like trees or other nested structures. Recursive Types are useful for representing hierarchical data structures with an arbitrary depth. https://www.typescriptlang.org/docs/handbook/advanced-types.html#recursive-types
Inference in Generics in TypeScript allows the compiler to infer the type parameters of generic functions based on the arguments passed to them. Inference in Generics is useful for reducing the need for explicit type annotations while maintaining flexibility and type safety. https://www.typescriptlang.org/docs/handbook/2/generics.html#type-inference
Abstract Classes in TypeScript are classes that cannot be instantiated directly and are meant to be extended by other classes. Abstract Classes are useful when you want to define a base class with shared behavior while enforcing certain methods to be implemented in derived classes. https://www.typescriptlang.org/docs/handbook/2/classes.html#abstract-classes
Overloads in TypeScript allow you to define multiple signatures for the same function, enabling the function to accept different combinations of arguments and return types. Overloads are useful when you need a single function to handle different input types or structures. https://www.typescriptlang.org/docs/handbook/2/functions.html#function-overloads
ReadonlyArray in TypeScript is a type that represents an array that cannot be modified. ReadonlyArray is useful when you want to ensure that an array is immutable and prevent any changes to its elements or length. https://www.typescriptlang.org/docs/handbook/2/objects.html#readonlyarray
ReturnType in TypeScript is a utility type that extracts the return type of a function. ReturnType is useful when you want to infer or enforce the type of a function’s return value in other parts of your code. https://www.typescriptlang.org/docs/handbook/utility-types.html#returntypetype
InstanceType in TypeScript is a utility type that extracts the instance type of a class or constructor function. InstanceType is useful when you need to work with instances of a class and want to ensure the correct type is used. https://www.typescriptlang.org/docs/handbook/utility-types.html#instancetypetype
NonNullable in TypeScript is a utility type that removes `null` and `undefined` from a given type. NonNullable is useful when you want to ensure that a type does not allow these values, making the code more predictable and less prone to runtime errors. https://www.typescriptlang.org/docs/handbook/utility-types.html#nonnullabletype
Record in TypeScript is a utility type that creates an object type with a specific set of keys and values of a specific type. Record is useful for mapping a set of keys to values of a uniform type, ensuring consistency across all properties. https://www.typescriptlang.org/docs/handbook/utility-types.html#recordkeystype
Exclude in TypeScript is a utility type that constructs a new type by excluding certain types from a union. Exclude is useful when you want to filter out specific types from a more general union type. https://www.typescriptlang.org/docs/handbook/utility-types.html#excludetype-excludedunion
Extract in TypeScript is a utility type that extracts specific types from a union. Extract is useful when you want to isolate particular types from a union type and operate only on those. https://www.typescriptlang.org/docs/handbook/utility-types.html#extracttype-union
Awaited in TypeScript is a utility type that helps extract the type of a value inside a Promise. Awaited is useful when working with asynchronous code and promises, ensuring that the correct type is inferred once the promise resolves. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-5.html#the-awaited-type-and-promise-improvements
ThisType in TypeScript is a marker interface that provides an explicit `this` type for an object or class. ThisType is useful for controlling the type of `this` in methods, allowing for better type safety in methods relying on `this`. https://www.typescriptlang.org/docs/handbook/utility-types.html#thistypetype
Key Remapping in TypeScript allows for renaming keys in Mapped Types using template literal types. Key Remapping is useful when you want to dynamically change the names of properties in types based on certain conditions. https://www.typescriptlang.org/docs/handbook/2/mapped-types.html#key-remapping-via-as
Object Destructuring in TypeScript is a syntax feature that allows you to extract values from objects and assign them to variables. Destructuring is useful for making code more concise, particularly when working with large or nested objects. https://www.typescriptlang.org/docs/handbook/variable-declarations.html#object-destructuring
Array Destructuring in TypeScript allows you to extract values from arrays and assign them to variables. Destructuring is especially useful when you need to work with specific elements of an array without manually accessing them by index. https://www.typescriptlang.org/docs/handbook/variable-declarations.html#array-destructuring
Optional Parameters in TypeScript allow you to define parameters that are not required when calling a function. Optional Parameters are useful when you want to give callers the option to omit certain arguments, offering more flexibility in function calls. https://www.typescriptlang.org/docs/handbook/2/functions.html#optional-parameters
Abstract Methods in TypeScript are methods declared in an Abstract Class without providing an implementation. Abstract Methods must be implemented by subclasses, ensuring that derived classes provide specific functionality for these methods. https://www.typescriptlang.org/docs/handbook/2/classes.html#abstract-classes-and-members
Type Parameters in TypeScript allow functions, classes, or interfaces to work with a variety of types rather than a single one. Type Parameters are specified within angle brackets (`<T>`), and they enable Generics to maintain type safety while allowing flexibility. https://www.typescriptlang.org/docs/handbook/2/generics.html#introduction
Readonly Tuple in TypeScript is a special type of Tuple where elements cannot be reassigned after initialization. Readonly Tuple is useful when you want to create a fixed-size, immutable array with specific types for each element. https://www.typescriptlang.org/docs/handbook/2/objects.html#readonly-tuple-types
Type Predicates in TypeScript are special return types that narrow down the type of a value within a conditional block. Type Predicates are useful when writing custom Type Guards, allowing you to inform the compiler about specific types after checking conditions. https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates
Rest Parameters in TypeScript allow you to pass a variable number of arguments to a function. Rest Parameters collect all remaining arguments into an array, making functions more flexible when dealing with multiple inputs. https://www.typescriptlang.org/docs/handbook/2/functions.html#rest-parameters-and-arguments
Default Parameters in TypeScript allow you to set default values for function parameters, so they are used when no argument is provided. Default Parameters make function calls more concise and reduce the need for additional code to handle missing arguments. https://www.typescriptlang.org/docs/handbook/2/functions.html#default-parameters
Private Fields in TypeScript are properties of a class prefixed with a `#`, making them accessible only within the class they are defined in. Private Fields enforce encapsulation, ensuring that these fields are not exposed outside the class. https://www.typescriptlang.org/docs/handbook/classes.html#private-fields
Public Fields in TypeScript are properties of a class that can be accessed both inside and outside the class. Public Fields are the default in TypeScript and allow free interaction with the property from any part of the code. https://www.typescriptlang.org/docs/handbook/2/classes.html#public-private-and-protected-modifiers
Protected Fields in TypeScript are properties that can only be accessed within the class and its subclasses. Protected Fields are useful when you want to expose properties to child classes but not to other parts of the code. https://www.typescriptlang.org/docs/handbook/2/classes.html#protected
Index Signatures in TypeScript define the type of properties that may not be known at compile time. Index Signatures allow for dynamic object keys, enabling developers to work with objects whose property names are not predefined. https://www.typescriptlang.org/docs/handbook/2/objects.html#index-signatures
StrictNullChecks in TypeScript is a compiler option that ensures `null` and `undefined` are only assignable to variables of their own types. StrictNullChecks are useful for preventing runtime errors related to unintentional `null` or `undefined` values. https://www.typescriptlang.org/tsconfig#strictNullChecks
Literal Inference in TypeScript is a feature where the compiler infers the literal type of a value, such as `“foo”` instead of `string`. Literal Inference is useful when you want to maintain specific values and avoid general types, which can help prevent bugs. https://www.typescriptlang.org/docs/handbook/2/narrowing.html#literal-inference
Conditional Types Distributivity in TypeScript refers to how conditional types distribute over union types. Distributivity is useful for transforming or filtering types in more complex type manipulations. https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
Type Guards in TypeScript are methods or expressions used to narrow the type of a variable in a specific scope. Type Guards are essential for safely handling multiple types in a function or conditional block, enabling safe access to properties and methods. https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-guards
Exhaustiveness Checking in TypeScript is a feature that ensures all possible cases in a Union Type are handled in a `switch` statement or conditional block. Exhaustiveness Checking helps prevent runtime errors by guaranteeing that every possible type is covered. https://www.typescriptlang.org/docs/handbook/2/narrowing.html#exhaustiveness-checking
Inferred Return Types in TypeScript allow the compiler to deduce the return type of a function based on the implementation. Inferred Return Types reduce the need for explicit type annotations, making code more concise while still preserving type safety. https://www.typescriptlang.org/docs/handbook/2/functions.html#return-type-inference
Inference Contextual Typing in TypeScript is a feature where the context in which a value is used helps determine its type. Contextual Typing is useful when working with functions or objects where the type of a value is inferred based on its usage. https://www.typescriptlang.org/docs/handbook/type-inference.html#contextual-typing
Declaration Merging in TypeScript allows multiple declarations with the same name to be combined into a single entity. Declaration Merging is useful when extending or augmenting existing modules, interfaces, or classes without rewriting them. https://www.typescriptlang.org/docs/handbook/declaration-merging.html
Augmenting Global Scope in TypeScript refers to extending or modifying types in the global namespace, often used when working with third-party libraries. Global Augmentation is useful when you need to add new methods or properties to global objects like `Window` or `Document`. https://www.typescriptlang.org/docs/handbook/declaration-merging.html#global-augmentation
Intersection of Unions in TypeScript is a technique for combining multiple union types to create more specific types that satisfy all the given unions. Intersection of Unions is useful for creating stricter types from broader ones, improving type safety. https://www.typescriptlang.org/docs/handbook/2/objects.html#intersection-types
Optional Chaining in TypeScript is a feature that allows safe access to nested properties without causing runtime errors if a property is `null` or `undefined`. Optional Chaining is useful for avoiding errors when dealing with deeply nested object structures. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#optional-chaining
Key Remapping in Mapped Types in TypeScript allows developers to change the keys of a Mapped Type dynamically using the `as` keyword. Key Remapping is useful for transforming the property names of types based on certain conditions. https://www.typescriptlang.org/docs/handbook/2/mapped-types.html#key-remapping-via-as
Literal Type Widening in TypeScript refers to the process where a literal type (like `“hello”`) is widened to a more general type (like `string`) unless explicitly annotated. Literal Type Widening helps ensure variables can store more general types unless constrained. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-inference
Type Compatibility in TypeScript is the concept that describes when one type can be assigned to another. Type Compatibility ensures that a value conforms to the expected type in assignments, function parameters, and return values. https://www.typescriptlang.org/docs/handbook/type-compatibility.html
Indexed Signatures in TypeScript allow types to define a set of properties with names that are not predefined, using an index signature like `[key: string]`. Indexed Signatures are useful for defining dynamic objects where properties are added at runtime. https://www.typescriptlang.org/docs/handbook/2/objects.html#index-signatures
Rest Types in TypeScript allow developers to create types that represent the remaining parameters or elements in a tuple or function signature. Rest Types are useful when working with functions or tuples that accept a variable number of arguments. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-0.html#variadic-tuple-types
Literal Unions in TypeScript are unions of specific literal types, such as `“apple” | “orange” | “banana”`. Literal Unions are useful for defining variables that can only have a predefined set of values, improving type safety in function arguments or configuration settings. https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-types
Template Literal Types in TypeScript allow developers to create types that are string literal unions, which are dynamically generated using template literal syntax. Template Literal Types are useful for constructing complex string types based on other types. https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
BigInt in TypeScript is a primitive data type that represents integers larger than the maximum safe integer value in JavaScript. BigInt is useful for dealing with large numerical values that exceed the limitations of regular numbers. https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-2.html
Namespace Import in TypeScript allows the entire content of a module to be imported into a single object using the `import * as` syntax. Namespace Import is useful when working with large modules or when you need to organize code into grouped imports. https://www.typescriptlang.org/docs/handbook/modules.html#re-exporting-declarations
STARTED OVER!
TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Below is a glossary of some of the most commonly used terms in TypeScript:
TypeScript: A programming language developed by Microsoft that builds on JavaScript by adding static types. This allows developers to catch errors earlier in the development process and helps with code quality and maintainability. It is commonly used in large-scale applications where type safety is a priority.
https://en.wikipedia.org/wiki/TypeScript
Interface: A key feature in TypeScript used to define the structure of an object. An Interface allows developers to specify what properties and methods an object should have without dictating how they should be implemented. This helps ensure that objects conform to a specific structure across the codebase.
https://www.typescriptlang.org/docs/handbook/interfaces.html
Type: The foundation of TypeScript's type system. Types represent the kinds of values that variables can hold, such as strings, numbers, or more complex data structures. Developers can define custom types to ensure that variables hold specific kinds of values, reducing errors during runtime.
https://www.typescriptlang.org/docs/handbook/basic-types.html
Union Types: A TypeScript feature that allows a variable to hold more than one type of value. By using a pipe symbol (`|`), developers can specify that a variable may be of one type or another, increasing flexibility while still maintaining type safety.
https://www.typescriptlang.org/docs/handbook/unions-and-intersections.html
Generics: A powerful feature in TypeScript that allows functions, classes, and interfaces to be defined with placeholders for types. This makes code more reusable and type-safe by allowing the same logic to work with different data types without sacrificing type checks.
https://www.typescriptlang.org/docs/handbook/generics.html
Modules: In TypeScript, modules are used to organize code into separate files and namespaces. This improves the maintainability of large projects by keeping related code together. Modules can export and import variables, functions, and classes, making them available across different parts of an application.
https://en.wikipedia.org/wiki/TypeScript
Decorators: A special feature in TypeScript that allows developers to modify the behavior of classes, methods, or properties. Decorators are commonly used in frameworks like Angular to add functionality, such as logging or validation, to existing code without modifying the underlying logic.
https://www.typescriptlang.org/docs/handbook/decorators.html
Enums: A data structure in TypeScript that allows developers to define a set of named constants. Enums are useful when you have a collection of related values, such as days of the week or status codes, that you want to represent in a more readable way.
https://www.typescriptlang.org/docs/handbook/enums.html
Type Inference: A feature of TypeScript that allows the compiler to automatically determine the type of a variable based on its value. This reduces the need for explicit type annotations and makes the code cleaner, while still enforcing type safety.
https://en.wikipedia.org/wiki/TypeScript
Any: A special type in TypeScript that can hold any kind of value. While this can be useful for maintaining compatibility with JavaScript or when the type of a value is unknown, it bypasses the strict type checking of TypeScript and is generally discouraged in favor of more specific types.
https://www.typescriptlang.org/docs/handbook/basic-types.html
Literal Types: A feature in TypeScript that allows you to specify exact values that a variable can have, rather than just its type. For example, a variable can be constrained to only the values `“yes”` or `“no”`, rather than just being of type `string`. This helps enforce stricter conditions and reduces errors by ensuring only predefined values are allowed.
https://www.typescriptlang.org/docs/handbook/literal-types.html
Type Aliases: A way in TypeScript to create a new name for a type, making it easier to reuse complex types throughout a codebase. Type Aliases allow developers to define more readable, concise, and maintainable code without having to rewrite long type definitions multiple times.
https://www.typescriptlang.org/docs/handbook/advanced-types.html
Intersection Types: A feature that allows developers to combine multiple types into one. When using Intersection Types, the resulting type must satisfy all the constraints of the individual types. This is useful when you need an object or variable to have properties from more than one type.
https://www.typescriptlang.org/docs/handbook/unions-and-intersections.html
Mapped Types: A feature that allows developers to create new types by transforming existing ones. Mapped Types are especially useful when working with large codebases that require creating variations of types, such as making all properties optional or readonly.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Readonly: A modifier in TypeScript that prevents properties of an object from being reassigned after they are initially set. The Readonly modifier is useful for ensuring that certain data remains constant after its initial definition, improving code stability and predictability.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytype
Tuple: A type in TypeScript that allows you to define an array with fixed types for each element. Unlike regular arrays, where all elements are of the same type, Tuples allow specific types for each position in the array, making it useful when you need to work with a fixed structure of values.
https://www.typescriptlang.org/docs/handbook/basic-types.html#tuple
Optional Properties: A feature that allows you to mark certain properties of an object as optional. This means that these properties may or may not be present in the object, and TypeScript will not enforce their presence, allowing for greater flexibility when designing interfaces and objects.
https://www.typescriptlang.org/docs/handbook/interfaces.html#optional-properties
Never: A special type in TypeScript that represents values that should never occur. It is typically used for functions that throw exceptions or never return, signaling to the type system that a value or condition is impossible.
https://www.typescriptlang.org/docs/handbook/basic-types.html#never
Void: A type used to indicate that a function does not return a value. In contrast to the `undefined` type, which is used for variables that hold no value, Void is used specifically for functions that do not return anything.
https://www.typescriptlang.org/docs/handbook/basic-types.html#void
Type Guards: A technique in TypeScript that allows you to narrow down the type of a variable within a conditional block. By using Type Guards, you can provide the compiler with additional information about the possible types of a variable, ensuring safer operations and avoiding runtime errors.
Keyof: A TypeScript operator that is used to extract the keys from an object type. The result is a union of string literals representing each key in the object. This is useful when working with object types and ensuring that code remains type-safe by referencing only valid keys.
https://www.typescriptlang.org/docs/handbook/2/keyof-types.html
Conditional Types: A feature in TypeScript that allows you to create types based on a condition. Conditional types evaluate whether a condition is true or false and return different types depending on the result. This provides greater flexibility when working with complex types and can help reduce redundancy in type definitions.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html
Abstract Classes: A type of class in TypeScript that cannot be instantiated directly. Abstract Classes are meant to serve as base classes for other classes, enforcing a structure or behavior that subclasses must implement. They are used to provide common functionality while requiring specific implementation details in subclasses.
https://www.typescriptlang.org/docs/handbook/classes.html#abstract-classes
Access Modifiers: A set of keywords in TypeScript—`public`, `private`, and `protected`—used to control the visibility of class members. Access Modifiers help encapsulate and protect data within classes by specifying which members can be accessed from outside the class or its subclasses.
https://www.typescriptlang.org/docs/handbook/classes.html#public-private-and-protected-modifiers
Static Methods: A type of method in TypeScript that belongs to the class itself rather than to instances of the class. Static Methods can be called without creating an instance of the class and are commonly used for utility functions or factory methods.
https://www.typescriptlang.org/docs/handbook/classes.html#static-properties
Decorators: Special functions in TypeScript that modify or enhance classes, methods, or properties. Decorators are commonly used in frameworks like Angular to add metadata or behaviors to existing code without altering its original structure.
https://www.typescriptlang.org/docs/handbook/decorators.html
Namespace: A feature in TypeScript that allows developers to organize code under a single, named scope. Namespaces help group related code together and prevent name collisions in large projects. While Modules have largely replaced Namespaces, they are still useful in some scenarios.
https://www.typescriptlang.org/docs/handbook/namespaces.html
Utility Types: A collection of built-in types provided by TypeScript that help manipulate and transform other types. Examples include `Partial`, `Readonly`, and `Pick`. Utility Types make it easier to work with complex types by providing shorthand for common type transformations.
https://www.typescriptlang.org/docs/handbook/utility-types.html
Type Assertions: A feature in TypeScript that allows developers to tell the compiler to treat a value as a specific type. Type Assertions are useful when you know more about the type of a value than the compiler does, but they should be used with caution to avoid potential runtime errors.
https://www.typescriptlang.org/docs/handbook/basic-types.html#type-assertions
Discriminated Unions: A pattern in TypeScript that combines Union Types with literal types and Type Guards to provide exhaustive checks for type safety. Discriminated Unions are useful for representing data structures where an object can take one of several shapes, and each shape can be differentiated by a specific property.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#discriminated-unions
Index Signatures: A feature in TypeScript that allows objects to have properties with dynamically determined names, rather than predefined ones. Index Signatures are used to describe types for objects that may have unknown keys, ensuring that all keys and their corresponding values conform to a specific type.
https://www.typescriptlang.org/docs/handbook/interfaces.html#indexable-types
Parameter Properties: A shorthand feature in TypeScript that allows class constructor parameters to be automatically assigned as class properties, reducing boilerplate code. By prefixing a parameter with an access modifier like `public` or `private`, you can define and initialize a class property in one step.
https://www.typescriptlang.org/docs/handbook/2/classes.html#parameter-properties
Non-null Assertion Operator: A TypeScript operator (`!`) used to tell the compiler that a value is non-null or non-undefined, even if the type system isn't able to infer that. This is useful when the developer knows a variable won't be null, but the compiler can't guarantee it.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator
Indexed Access Types: A feature in TypeScript that allows developers to retrieve the type of a property from an object type using its key. Indexed Access Types are useful when working with objects where you need to reference the type of a specific property dynamically.
https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
Optional Chaining: A feature in TypeScript that allows developers to safely access deeply nested properties on an object without having to check if each intermediate property exists. Using the `?.` operator, Optional Chaining helps avoid runtime errors when properties are undefined or null.
https://www.typescriptlang.org/docs/handbook/2/optional-chaining.html
BigInt: A primitive type in TypeScript that represents arbitrarily large integers. BigInt is useful for working with numbers beyond the safe integer range for the Number type, making it suitable for cryptography, large computations, and precise calculations.
https://www.typescriptlang.org/docs/handbook/basic-types.html#bigint
This Type: A special type in TypeScript used to represent the type of the current object instance in methods or within object literals. This Type helps ensure that methods are called with the correct instance context, improving type safety in object-oriented code.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#this-types
Unknown: A type in TypeScript that represents any value, similar to Any, but with the key difference that no operations can be performed on an Unknown type without first narrowing it down through type checking. This provides a safer alternative to using Any for unknown values.
https://www.typescriptlang.org/docs/handbook/basic-types.html#unknown
Exhaustiveness Checking: A pattern used in TypeScript to ensure that all possible cases in a Union Type or Discriminated Union are handled. This is often implemented by adding a `never` case to catch unhandled cases, ensuring type safety and completeness in code.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#exhaustiveness-checking
Intrinsic String Manipulation Types: A set of built-in types in TypeScript that allows developers to perform transformations on string types, such as Uppercase, Lowercase, Capitalize, and Uncapitalize. These types are useful when working with string literal types and want to enforce specific casing rules.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html#string-manipulation
Type Parameters: A core concept in TypeScript that allows developers to create functions, classes, or interfaces that can work with a variety of types. By using Type Parameters, developers can write reusable code that operates on different types without sacrificing type safety.
https://www.typescriptlang.org/docs/handbook/generics.html#generic-constraints
Recursive Types: A feature in TypeScript where a type can refer to itself within its definition. Recursive Types are useful for describing structures like trees or nested objects where the type of an object can contain instances of itself.
https://www.typescriptlang.org/docs/handbook/2/recursive-types.html
Function Overloading: A feature in TypeScript that allows multiple function signatures for a single function. Function Overloading helps define functions that can handle different argument types or numbers of arguments, providing more flexibility and clarity in function definitions.
https://www.typescriptlang.org/docs/handbook/functions.html#overloads
Key Remapping: A feature in Mapped Types that allows developers to transform object types by changing their keys. Key Remapping is useful when you want to rename object properties dynamically while preserving their value types.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html#key-remapping-via-as
Infer Keyword: A TypeScript keyword used within conditional types to extract and capture types for later use. Infer allows developers to work with types indirectly and is commonly used in advanced type manipulation scenarios.
Indexed Types: A concept in TypeScript where an index signature allows you to define types for objects that are accessed via string or number keys. Indexed Types are helpful when working with objects whose property names are not known in advance but follow a consistent type pattern.
https://www.typescriptlang.org/docs/handbook/interfaces.html#indexable-types
Private Fields: A feature in TypeScript that allows developers to create class fields that cannot be accessed outside of the class. Denoted with a `#` symbol, Private Fields enforce strict encapsulation, ensuring that internal class data remains protected from external access.
https://www.typescriptlang.org/docs/handbook/2/classes.html#private-fields
ReadonlyArray: A specialized array type in TypeScript that prevents modification of the array's elements. ReadonlyArray ensures that once an array is created, its contents cannot be changed, providing immutable data structures for safer code.
https://www.typescriptlang.org/docs/handbook/interfaces.html#readonlyarray
Optional Parameters: A feature in TypeScript that allows function parameters to be marked as optional, meaning they may or may not be provided by the caller. Optional Parameters are denoted with a `?` symbol, making functions more flexible without requiring all arguments to be passed.
https://www.typescriptlang.org/docs/handbook/functions.html#optional-and-default-parameters
Constructor Functions: In TypeScript, Constructor Functions are special functions used to create and initialize objects. They serve as a template for instantiating objects with specific properties and methods, forming the basis for classes and object-oriented programming in TypeScript.
https://www.typescriptlang.org/docs/handbook/2/classes.html#constructors
Abstract Methods: A method defined within an Abstract Class that has no implementation in the base class. Abstract Methods must be implemented by subclasses, enforcing a contract that ensures specific functionality will be provided by any class inheriting from the abstract base.
https://www.typescriptlang.org/docs/handbook/classes.html#abstract-classes
Rest Parameters: A feature in TypeScript that allows a function to accept an indefinite number of arguments as an array. Rest Parameters are useful for functions that need to handle a flexible number of inputs, while still ensuring type safety for each argument.
https://www.typescriptlang.org/docs/handbook/functions.html#rest-parameters
Tuple Types: A specific form of Tuple in TypeScript where each element in the array is restricted to a specific type. Tuple Types allow more control over the types of individual elements within arrays, as opposed to arrays that contain elements of the same type.
https://www.typescriptlang.org/docs/handbook/basic-types.html#tuple
Optional Chaining Operator: A syntax feature that allows developers to safely access properties deep within an object or call functions that might not exist, without having to check each level of the object for `null` or `undefined`. This operator (`?.`) helps prevent runtime errors by returning `undefined` if a reference is invalid.
https://www.typescriptlang.org/docs/handbook/2/optional-chaining.html
Spread Operator: A feature in TypeScript that allows an iterable, such as an array or object, to be expanded into individual elements or properties. The Spread Operator is often used in functions to pass arrays as individual arguments or to clone and merge objects.
https://www.typescriptlang.org/docs/handbook/functions.html#rest-parameters-and-arguments
Readonly Tuple: A TypeScript type that extends Tuple Types by making the elements of the tuple immutable. Readonly Tuples ensure that the values within the tuple cannot be reassigned after their initial declaration, providing stricter control over the data.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytupletype
Decorator Factories: A feature in TypeScript that allows developers to create Decorators that are configurable. Decorator Factories return a decorator function based on the input arguments, making them more versatile and customizable for use cases like dependency injection or logging.
https://www.typescriptlang.org/docs/handbook/decorators.html#decorator-factories
Default Parameters: A feature that allows developers to assign default values to function parameters. If no argument is passed for a parameter with a default value, TypeScript will automatically use the default, simplifying function calls and making the code more readable.
https://www.typescriptlang.org/docs/handbook/functions.html#optional-and-default-parameters
Omit: A built-in Utility Type in TypeScript that creates a new type by removing one or more keys from an existing type. Omit is useful for modifying complex types when you want to exclude certain properties from an object.
https://www.typescriptlang.org/docs/handbook/utility-types.html#omittype-keys
Partial: A Utility Type that makes all properties of a given type optional. Partial is helpful when you need to create objects that have only some of the properties of an existing type, making it easier to work with incomplete data.
https://www.typescriptlang.org/docs/handbook/utility-types.html#partialtype
Pick: A built-in Utility Type in TypeScript that creates a new type by selecting specific properties from an existing type. Pick is useful when you only need a subset of properties from a larger object type, allowing for more focused and concise type definitions.
https://www.typescriptlang.org/docs/handbook/utility-types.html#picktype-keys
Intersection Types: A feature in TypeScript that combines multiple types into a single type. With Intersection Types, the resulting type must satisfy all the requirements of the individual types, allowing for precise type definitions that combine multiple behaviors or structures.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types
Exclamation Mark: Also known as the Non-null Assertion Operator (`!`), this operator is used to tell the TypeScript compiler that a variable is not null or undefined, even if the compiler cannot infer that. It is a way to bypass type checking for specific values when the developer is confident about their state.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator
Index Signatures: A feature in TypeScript that allows the definition of types for objects with dynamic or unknown keys. Index Signatures specify that all keys in an object must conform to a specific type, and the values associated with those keys must also follow a defined type.
https://www.typescriptlang.org/docs/handbook/interfaces.html#index-signatures
Key Remapping: In Mapped Types, Key Remapping allows developers to change the names of keys in a type while preserving the original type structure. It is useful for transforming types when working with dynamic property names in an object type.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html#key-remapping-via-as
Symbol: A primitive data type in TypeScript used to create unique identifiers that are guaranteed to be unique across different parts of the codebase. Symbols are often used as property keys in objects to avoid name collisions and ensure that the properties are not accidentally overwritten.
https://www.typescriptlang.org/docs/handbook/symbols.html
Type Narrowing: A feature in TypeScript where the type of a variable is reduced to a more specific type within a conditional block. Type Narrowing helps the compiler determine the exact type of a value at runtime, providing more precise type checks and reducing errors.
Template Literal Types: A feature that allows developers to construct string literal types using interpolation, similar to string templates in JavaScript. Template Literal Types can be used to create new types based on patterns, such as combining multiple string literals into a single type.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
This Parameter: In TypeScript, the This Parameter allows functions to define the type of `this` explicitly, ensuring that methods are called with the correct instance context. It improves the handling of `this` in functions, especially when used within object literals or classes.
https://www.typescriptlang.org/docs/handbook/functions.html#this-parameters
Module Resolution: The process by which TypeScript locates and imports modules in a codebase. Module Resolution defines how relative and non-relative module imports are resolved, determining the files that should be included in a TypeScript project.
https://www.typescriptlang.org/docs/handbook/module-resolution.html
String Literal Types: A type in TypeScript that allows variables to hold only specific string values, rather than any string. String Literal Types are useful when you need to restrict a variable to a predefined set of string values, such as `'start'`, `'stop'`, or `'pause'`.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#string-literal-types
Constructor Type: A type that describes the shape of a constructor function. Constructor Types allow you to define types for classes that include both the constructor signature and the types of the properties and methods that instances of the class will have.
https://www.typescriptlang.org/docs/handbook/2/functions.html#construct-signatures
Conditional Return Types: A feature in TypeScript that allows you to define different return types for a function based on the types of the input parameters. This enables functions to return different types depending on their input, improving type safety and flexibility.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html
Readonly Modifier: A modifier that ensures that properties of an object cannot be reassigned after their initial value is set. The Readonly Modifier is used to create immutable properties, ensuring that they remain constant throughout the program.
https://www.typescriptlang.org/docs/handbook/interfaces.html#readonly-properties
Symbol.iterator: A well-known symbol in TypeScript that defines the default iterator for objects. Objects with the `Symbol.iterator` method are iterable, meaning they can be used in loops like `for…of`. This allows custom objects to define how they should be iterated over.
Awaited Type: A built-in type in TypeScript that represents the type that a promise resolves to. Awaited Type helps define the type that a promise will return once resolved, making asynchronous code more predictable and type-safe.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-5.html#the-awaited-type
Typeof Type Operator: A TypeScript operator that allows developers to refer to the type of a value. By using the `typeof` operator, you can define types based on the actual value of a variable, making type definitions more dynamic and flexible.
https://www.typescriptlang.org/docs/handbook/2/typeof-types.html
Function Type: A specific type in TypeScript that represents the signature of a function, including the types of its parameters and its return type. Function Types allow developers to enforce specific function shapes throughout their codebase, ensuring consistent function usage.
https://www.typescriptlang.org/docs/handbook/2/functions.html#function-type-expressions
Call Signatures: A feature in TypeScript that defines the parameter and return types of functions within objects, classes, or interfaces. Call Signatures enable type checking for function-like entities that aren't declared as standalone functions.
https://www.typescriptlang.org/docs/handbook/interfaces.html#call-signatures
Distributive Conditional Types: A concept in TypeScript where conditional types are applied across the members of union types, resulting in types that are distributed over each member of the union. This enables more granular type manipulations and fine-tuned type safety.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
Type Predicate: A special return type for functions in TypeScript that narrows down the type of its argument based on the function’s logic. Type Predicates allow you to define functions that tell the compiler the type of a variable at runtime, enhancing type safety in conditional blocks.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates
Decorator Metadata: A feature in TypeScript that provides runtime metadata about decorators applied to classes, methods, or properties. Decorator Metadata is often used in combination with frameworks like Angular to allow for reflection on class properties or methods at runtime.
https://www.typescriptlang.org/docs/handbook/decorators.html#metadata
Constructor Overloading: A feature in TypeScript that allows a class to have multiple constructor signatures, supporting different sets of parameters. Constructor Overloading makes classes more flexible by allowing multiple ways to instantiate them while maintaining strict type checking.
https://www.typescriptlang.org/docs/handbook/2/classes.html#constructors
Module Augmentation: A feature in TypeScript that allows developers to extend existing modules with additional functionality. Module Augmentation is useful when working with third-party libraries where you need to add types or functionality without modifying the original module.
https://www.typescriptlang.org/docs/handbook/declaration-merging.html#module-augmentation
Ambient Declarations: A type of declaration in TypeScript that tells the compiler about types or objects that exist in the environment but are not directly defined in the code. Ambient Declarations are often used to describe external libraries or APIs, ensuring they can be safely used in a TypeScript project.
https://www.typescriptlang.org/docs/handbook/declaration-files/by-example.html
ReadonlyArray<T>: A type in TypeScript that represents an immutable array, where elements cannot be added, removed, or modified. ReadonlyArray is useful for enforcing immutability when working with data structures that should not be changed after initialization.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlyarraytype
Type Compatibility: A concept in TypeScript where types are considered compatible based on their structure rather than their explicit declarations. Type Compatibility allows TypeScript to enforce type safety while being flexible about how types are defined and used.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html
Callable Interfaces: An interface in TypeScript that defines a function signature, allowing objects to be both callable and structured with properties or methods. Callable Interfaces provide a way to define objects that function like functions but also contain additional metadata.
https://www.typescriptlang.org/docs/handbook/interfaces.html#callable-interfaces
Constructor Signature: A specific type definition in TypeScript that describes the signature of a constructor function. Constructor Signatures define the parameters that are accepted when instantiating a class, ensuring type-safe object creation.
https://www.typescriptlang.org/docs/handbook/2/functions.html#construct-signatures
Unknown Type: A top type in TypeScript that represents any possible value but requires type narrowing before any operations can be performed on it. The Unknown Type is safer than the Any type because it forces type checks before accessing the value’s properties or methods.
https://www.typescriptlang.org/docs/handbook/basic-types.html#unknown
Partial Class Implementations: A feature in TypeScript that allows a class to implement only part of an interface, leaving some methods unimplemented. This can be useful in scenarios where a base class provides default functionality, and subclasses are responsible for implementing the remaining parts.
https://www.typescriptlang.org/docs/handbook/interfaces.html
Type Assertion: A mechanism in TypeScript that allows developers to manually override the type inferred by the compiler. Type Assertion is used when the developer knows more about the type of a value than TypeScript does, allowing for more control over type checking.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#type-assertions
Declaration Merging: A feature in TypeScript where two or more separate declarations of the same name are combined into a single definition. Declaration Merging is commonly used for merging interfaces, modules, or enums, allowing flexibility in extending types across different parts of a codebase.
https://www.typescriptlang.org/docs/handbook/declaration-merging.html
Default Type Parameters: A feature in TypeScript that allows generic types to have default values for their type parameters. Default Type Parameters provide flexibility in defining generics without forcing users to supply a type argument if the default suffices.
https://www.typescriptlang.org/docs/handbook/2/generics.html#default-type-parameters
Intersection Type Guards: A feature that allows developers to use Type Guards to ensure a value satisfies multiple types. Intersection Type Guards are essential when working with Intersection Types to narrow down the type to one that satisfies all constraints.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types
Utility Type: A set of predefined types in TypeScript that helps with common type transformations, such as `Pick`, `Omit`, and `Partial`. Utility Types make it easier to manipulate and transform complex types without having to manually define each variation.
https://www.typescriptlang.org/docs/handbook/utility-types.html
Mapped Tuple Types: A feature that allows developers to apply transformations to all elements of a tuple type. Mapped Tuple Types are useful when you need to create new tuple types by transforming each element of the original tuple based on a rule or mapping function.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Conditional Inference: A technique in TypeScript where the `infer` keyword is used within a conditional type to extract types based on conditions. Conditional Inference allows for more dynamic type manipulation, making the type system more expressive and flexible.
Branded Types: A strategy in TypeScript that allows you to create more distinct types by adding unique “brands” to primitive types. Branded Types are used to distinguish between types that may have similar structures but represent different concepts, ensuring type safety in specific scenarios.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#type-aliases
Type Parameters with Constraints: A feature that allows generic Type Parameters to be restricted by a specific type. Type Parameters with Constraints ensure that the type argument provided for a generic must conform to the specified constraint, enhancing type safety and flexibility.
https://www.typescriptlang.org/docs/handbook/generics.html#generic-constraints
Strict Null Checks: A compiler option in TypeScript that enforces stricter handling of `null` and `undefined` values. With Strict Null Checks enabled, TypeScript requires explicit checks before using variables that may hold `null` or `undefined`, improving type safety and reducing runtime errors.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#strict-null-checks
Overlapping Types: A situation in TypeScript where multiple types share common properties or structure. Overlapping Types can create ambiguity when working with union or intersection types, so it's important to use Type Guards or Type Assertions to clarify the type.
Private Modifier: A keyword in TypeScript that restricts access to class members, ensuring that properties or methods marked as Private cannot be accessed from outside the class. This helps with encapsulation, hiding internal implementation details and exposing only the necessary functionality.
https://www.typescriptlang.org/docs/handbook/2/classes.html#private
Protected Modifier: A keyword in TypeScript that allows class members to be accessed within the class and its subclasses, but not from outside. Protected Modifier is useful for maintaining encapsulation while still allowing inheritance to access certain members.
https://www.typescriptlang.org/docs/handbook/2/classes.html#protected
Indexed Access Type: A feature in TypeScript that allows you to retrieve the type of a property within an object using its key. Indexed Access Types enable dynamic type lookups, providing type safety when accessing properties in complex objects.
https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
String Index Signature: A type of index signature in TypeScript that allows objects to have string keys with values of a specific type. String Index Signatures are useful when defining objects with dynamic property names, such as dictionaries or key-value maps.
https://www.typescriptlang.org/docs/handbook/interfaces.html#indexable-types
Key Remapping with as: A feature in Mapped Types that allows you to rename keys when transforming object types. Key Remapping with as is particularly useful when you need to create new types with modified key names, while preserving the structure of the original object.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html#key-remapping-via-as
Literal Inference: A mechanism in TypeScript where literal types are inferred from values, rather than general types like `string` or `number`. Literal Inference allows the compiler to infer more specific types, providing stricter type checks for variables that should only hold specific values.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html#string-literal-types
Exhaustive Type Checking: A technique in TypeScript where all possible cases in a union type are checked, ensuring that no case is left unhandled. Exhaustive Type Checking is commonly used in Discriminated Unions to enforce that every possible variant of a type is accounted for.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#discriminated-unions
Rest Element in Tuple Types: A feature in TypeScript that allows the last element of a tuple type to be a Rest Element, capturing any number of additional elements. This provides flexibility when defining tuple types that can vary in length while preserving type safety.
https://www.typescriptlang.org/docs/handbook/2/functions.html#rest-parameters-and-tuples
Infer Type: A keyword used within conditional types that allows TypeScript to infer a type from the structure of a value or expression. The Infer Type keyword enables more advanced type manipulation by capturing types that are determined during type evaluation.
Exhaustiveness Checking in Unions: A pattern in TypeScript that ensures all possible cases of a union type are covered by using techniques like Type Guards or switch statements. Exhaustiveness Checking in Unions prevents runtime errors by making sure every possible value is handled in the logic.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#exhaustiveness-checking
Type Widening: A process in TypeScript where a literal type, such as `'hello'`, is widened to a more general type, such as `string`, when no explicit type is provided. Type Widening occurs automatically in TypeScript unless prevented by specific type annotations.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-inference
Literal Type Narrowing: A feature in TypeScript where the type of a value is narrowed to a more specific literal type based on how the value is used. Literal Type Narrowing allows for precise type checks when dealing with constants or specific string, number, or boolean values.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#literal-types
Constraint-Based Generics: A type of generics in TypeScript that allows type parameters to be restricted by a particular type using the `extends` keyword. Constraint-Based Generics ensure that the type passed to a generic function or class adheres to a certain structure or interface.
https://www.typescriptlang.org/docs/handbook/2/generics.html#generic-constraints
Exact Optional Property Types: A feature that provides stricter handling of optional properties by ensuring that explicitly `undefined` values are treated differently from missing values. Exact Optional Property Types help catch edge cases where properties might be mistakenly omitted or set to `undefined`.
Readonly Modifier for Parameters: A feature in TypeScript that ensures function parameters are immutable within the function body by marking them as Readonly. This helps prevent accidental mutation of function arguments, enhancing code safety.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytype
Template Literal Types with Interpolation: A feature in TypeScript that allows types to be generated dynamically by interpolating string literal types. Template Literal Types with Interpolation are useful for creating types that combine string literals, enabling more flexible type creation.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html#string-literal-types
Optional Tuple Elements: A feature in TypeScript that allows specific elements within a tuple to be optional. Optional Tuple Elements provide greater flexibility when working with tuples, making it possible to have tuples of varying lengths while still enforcing type checks on the known elements.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-0.html#variadic-tuple-types
Abstract Constructor Types: A feature that defines constructor types for abstract classes. Abstract Constructor Types allow developers to define the signature for creating instances of subclasses without allowing direct instantiation of the abstract class itself.
https://www.typescriptlang.org/docs/handbook/2/classes.html#abstract-classes
Type Alias: A feature in TypeScript that allows developers to create a new name for a type. Type Alias is especially useful when working with complex types like unions, intersections, or tuples, providing a more readable and maintainable way to define and reuse types throughout the code.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#type-aliases
Keyof Operator: A TypeScript operator that returns a union of string literals representing the keys of a given object type. The Keyof Operator is useful for creating dynamic and type-safe mappings between keys and values in object types.
https://www.typescriptlang.org/docs/handbook/2/keyof-types.html
Structural Typing: A system in TypeScript where types are compatible based on their structure rather than their explicit declarations. In Structural Typing, two types are considered the same if they have the same shape, even if they were declared independently.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html
Declaration Files: Files in TypeScript with the `.d.ts` extension that describe the shape of existing JavaScript code to enable type checking. Declaration Files are useful for adding static typing to third-party libraries that do not have their own TypeScript types.
https://www.typescriptlang.org/docs/handbook/declaration-files/introduction.html
Module Bundling: The process of combining multiple TypeScript or JavaScript files into a single file or a few smaller files for efficient loading in the browser. Module Bundling helps optimize web applications by reducing the number of requests made to load different modules.
https://www.typescriptlang.org/docs/handbook/module-resolution.html
Ambient Modules: A special kind of module declaration in TypeScript used to describe external modules that exist but are not implemented in the current codebase. Ambient Modules are useful for integrating with third-party libraries or tools that do not provide their own type definitions.
https://www.typescriptlang.org/docs/handbook/modules.html#ambient-modules
Intersection of Conditional Types: A type system feature where conditional types can be combined using intersections. Intersection of Conditional Types provides greater flexibility by allowing conditional logic to apply across multiple types simultaneously, refining the type output.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html
Type Parameters in Interfaces: A way to make interfaces generic by adding type parameters. Type Parameters in Interfaces allow developers to define interfaces that work with multiple types, making the codebase more flexible and reusable when working with complex data structures.
https://www.typescriptlang.org/docs/handbook/2/generics.html
Type Declaration Merging: A feature in TypeScript that allows the same type name to be declared multiple times, with the compiler merging them into a single type. Type Declaration Merging is commonly used to extend existing types, especially when working with third-party libraries.
https://www.typescriptlang.org/docs/handbook/declaration-merging.html
Distributive Conditional Types: A mechanism in TypeScript that applies conditional logic across each member of a union type, distributing the conditional check over each type in the union. Distributive Conditional Types help create more precise type transformations for complex type systems.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
Mapped Types: A feature in TypeScript that allows developers to transform existing object types into new ones by iterating over the keys of an object. Mapped Types are useful for creating variations of types, such as making properties optional or readonly.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Intrinsic Types: Special built-in types in TypeScript that represent basic values such as `string`, `number`, and `boolean`. Intrinsic Types are fundamental to the type system and are used to define variables, function arguments, and return types.
https://www.typescriptlang.org/docs/handbook/basic-types.html
Tuple Inference: A type system feature that allows TypeScript to infer the types of elements within a tuple automatically. Tuple Inference ensures that when tuples are created, each element’s type is accurately inferred without needing explicit annotations.
https://www.typescriptlang.org/docs/handbook/basic-types.html#tuple
Function Overloads: A feature that allows functions to be defined with multiple signatures, each handling different parameter types or numbers of arguments. Function Overloads provide more flexible function definitions while maintaining strict type checking.
https://www.typescriptlang.org/docs/handbook/functions.html#overloads
Unknown Type Narrowing: A technique used to safely work with the Unknown Type, which represents any value. Through conditional checks, developers can narrow the type of an unknown variable, allowing safe operations without resorting to Any.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#unknown
Variadic Tuple Types: A type in TypeScript that supports tuples of varying lengths, allowing flexible handling of tuples with different numbers of elements. Variadic Tuple Types are often used in functions with rest parameters to ensure type safety.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-0.html#variadic-tuple-types
Namespace Import: A way to import all exports from a module into a single namespace. In TypeScript, Namespace Import allows developers to group all imported values under a common alias, making module usage more organized and concise.
https://www.typescriptlang.org/docs/handbook/modules.html#namespace-imports
Readonly Modifier for Arrays: A type modifier in TypeScript that ensures that the elements of an array cannot be changed after their initialization. The Readonly Modifier for Arrays is useful for creating immutable data structures.
https://www.typescriptlang.org/docs/handbook/interfaces.html#readonlyarray
Module Aliases: A feature in TypeScript that allows developers to create custom paths or names for modules when importing them. Module Aliases simplify large-scale project structure by enabling easier access to deeply nested modules without relative paths.
https://www.typescriptlang.org/docs/handbook/module-resolution.html#path-mapping
Type Inference in Generics: A feature that allows TypeScript to automatically infer the type parameters of a generic function or class based on the arguments provided. Type Inference in Generics reduces the need for explicit type annotations, making the code more concise while retaining type safety.
https://www.typescriptlang.org/docs/handbook/2/generics.html
Optional Chaining: A feature in TypeScript that allows you to safely access deeply nested object properties without having to check each level for `null` or `undefined`. Optional Chaining uses the `?.` operator and simplifies code by eliminating repetitive checks.
https://www.typescriptlang.org/docs/handbook/2/optional-chaining.html
Nullish Coalescing: A feature in TypeScript that allows you to provide a fallback value when a variable is `null` or `undefined`. The `??` operator ensures that only `null` or `undefined` trigger the fallback, while other falsy values like `0` or `` are treated as valid.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#nullish-coalescing
Object Spread and Rest: A feature in TypeScript that allows for spreading properties from one object into another or extracting remaining properties into a separate object. Object Spread and Rest makes it easier to work with object manipulation in a concise manner.
https://www.typescriptlang.org/docs/handbook/variable-declarations.html#object-spread-and-rest
Readonly Tuple: A tuple type in TypeScript where the elements are immutable after creation. The Readonly Tuple type ensures that the values within the tuple cannot be changed, enforcing immutability for tuple-based data structures.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytupletype
Indexed Access Types: A feature in TypeScript that allows you to access the type of a property on an object type dynamically using an index. Indexed Access Types improve type safety when accessing object properties using dynamic keys.
https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
Type Guard Functions: Functions in TypeScript that return a Type Predicate to narrow down the type of a variable. Type Guard Functions allow the compiler to refine types within a code block, enabling safer operations on variables of unknown or union types.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-type-predicates
Rest Parameters in Tuple Types: A feature that allows tuples to capture any number of additional elements using the rest (`…`) operator. Rest Parameters in Tuple Types allow for more flexible handling of tuples with variable lengths while maintaining type safety.
https://www.typescriptlang.org/docs/handbook/2/functions.html#rest-parameters-and-tuples
Distributive Conditional Types: A type system feature in TypeScript that applies conditional logic across union types. Distributive Conditional Types allow more complex type transformations by distributing conditional types over each member of a union.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
Non-null Assertion Operator: A syntax (`!`) in TypeScript that allows developers to assert that a value is not `null` or `undefined`. The Non-null Assertion Operator is useful when the developer knows a value is safe, even though the compiler cannot infer it.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#non-null-assertion-operator
Optional Tuple Elements: A feature in TypeScript that allows tuples to have optional elements. Optional Tuple Elements provide flexibility in defining tuples with varying lengths, where some elements may or may not be present.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-0.html#variadic-tuple-types
Constructor Functions: In TypeScript, constructor functions are used to initialize objects. These functions are called when a new instance of a class is created and allow you to set up initial property values. TypeScript supports type checking for constructor functions to ensure proper initialization.
https://www.typescriptlang.org/docs/handbook/2/classes.html#constructors
BigInt: A primitive type in TypeScript that represents arbitrarily large integers. BigInt allows for mathematical operations on numbers beyond the safe integer limit of the Number type, making it essential for use cases like cryptography or large financial calculations.
https://www.typescriptlang.org/docs/handbook/basic-types.html#bigint
Instanceof Type Guard: A type guard in TypeScript that checks whether an object is an instance of a specific class. The Instanceof Type Guard allows the compiler to narrow the type of a variable based on the result of the check, improving runtime type safety.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-instanceof
Async/Await: A modern way to handle asynchronous operations in TypeScript by using `async` functions and the `await` keyword. Async/Await simplifies working with promises by allowing asynchronous code to be written in a synchronous style.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-2-1.html#asyncawait
Property Decorators: Special functions in TypeScript that are applied to class properties to add metadata or modify behavior. Property Decorators are commonly used in frameworks like Angular to add functionality such as validation or dependency injection.
https://www.typescriptlang.org/docs/handbook/decorators.html#property-decorators
Return Type Inference: A feature where TypeScript automatically infers the return type of a function based on the values it returns. Return Type Inference reduces the need for explicit type annotations while maintaining type safety.
https://www.typescriptlang.org/docs/handbook/functions.html#return-type-inference
Declare Keyword: Used in TypeScript to tell the compiler that a variable, function, or class exists in the global scope or external environment. The Declare Keyword is commonly used in Ambient Declarations to describe third-party libraries.
https://www.typescriptlang.org/docs/handbook/declaration-files/by-example.html
Intersection Type Inference: A feature that allows TypeScript to infer the most specific common type from a combination of types in an intersection. Intersection Type Inference ensures that the resulting type satisfies all constraints of the intersected types.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types
Decorators for Method Parameters: A feature in TypeScript that allows decorators to be applied to method parameters. These Decorators can modify the behavior or metadata associated with a specific parameter within a method, often used in dependency injection systems.
https://www.typescriptlang.org/docs/handbook/decorators.html#parameter-decorators
TypeScript’s Utility Types: Predefined types in TypeScript that simplify common type transformations. These include `Partial`, `Required`, `Readonly`, and `Pick`, helping developers perform complex type operations with minimal code.
https://www.typescriptlang.org/docs/handbook/utility-types.html
Typeof Type Guards: A feature in TypeScript that allows developers to check the type of a variable at runtime using the `typeof` operator. Typeof Type Guards enable type narrowing based on basic types like `string`, `number`, and `boolean`, improving the accuracy of type checks.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#typeof-type-guards
Exhaustive Switch Checks: A pattern in TypeScript where a `switch` statement checks all possible values of a union type. If a case is missed, the compiler can flag it as an error, ensuring that all cases are handled and increasing the robustness of the code.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#exhaustiveness-checking
Callable Types: In TypeScript, callable types allow interfaces and object types to be defined with call signatures, enabling them to act like functions. Callable Types provide flexibility for designing objects that can be invoked as functions while still carrying properties or methods.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#interfaces-with-call-signatures
Partial Type: A built-in Utility Type in TypeScript that makes all properties of a given type optional. Partial Type is useful for working with objects where only some of the properties need to be set or passed, enhancing flexibility in type definitions.
https://www.typescriptlang.org/docs/handbook/utility-types.html#partialtype
Generic Type Inference: A feature where TypeScript can automatically infer the types used in generic functions or classes based on the types of the provided arguments. Generic Type Inference reduces the need for explicit type annotations, simplifying code while maintaining type safety.
https://www.typescriptlang.org/docs/handbook/2/generics.html
Indexed Signatures: A feature in TypeScript that allows object types to be defined with dynamic keys, meaning the keys are not known in advance. Indexed Signatures ensure that all dynamically named properties in an object adhere to a specified type.
https://www.typescriptlang.org/docs/handbook/interfaces.html#index-signatures
Module Resolution Strategy: In TypeScript, the module resolution strategy defines how imports are resolved to actual files in a project. There are two strategies: Classic and Node. The module resolution strategy ensures that dependencies are correctly loaded in both client and server environments.
https://www.typescriptlang.org/docs/handbook/module-resolution.html
TypeScript Path Mapping: A feature that allows custom module paths to be defined in a project using the `paths` property in the `tsconfig.json` file. Path Mapping simplifies the import statements by avoiding relative paths and organizing modules better.
https://www.typescriptlang.org/docs/handbook/module-resolution.html#path-mapping
Readonly Modifier for Class Properties: A modifier in TypeScript that ensures that class properties cannot be reassigned after they are initialized. The Readonly Modifier enforces immutability within class definitions, helping maintain integrity for object properties.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytype
Const Assertions: A feature in TypeScript where the `const` keyword is used with an assertion (`as const`) to infer the most specific types for values, such as literal types for objects or arrays. Const Assertions help preserve immutability and ensure that values remain unchanged.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-4.html#const-assertions
Literal Type Widening: A feature in TypeScript where a literal type (e.g., `'hello'`) is automatically widened to a broader type (e.g., `string`) if no explicit type is specified. Literal Type Widening can be controlled by using type annotations to preserve specific literal types.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-inference
Exhaustive Union Type Checks: A pattern in TypeScript where all possible cases of a Union Type are covered using techniques like switch statements or Type Guards. This ensures that code handles every variant of a union, preventing runtime errors.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#exhaustiveness-checking
Unknown Type: A top type in TypeScript that represents any value, similar to Any, but requires type narrowing before any operations can be performed. Unknown Type offers more safety than Any by forcing developers to explicitly check the type before use.
https://www.typescriptlang.org/docs/handbook/basic-types.html#unknown
Module Declaration: A feature in TypeScript that allows developers to declare the structure of modules, especially external modules that don’t have their own type definitions. Module Declarations ensure type safety when importing third-party libraries.
https://www.typescriptlang.org/docs/handbook/modules.html
Augmented Modules: A technique where TypeScript modules can be extended by adding new properties or methods to existing module definitions. Augmented Modules are useful for integrating additional functionality into third-party libraries without altering their original source code.
https://www.typescriptlang.org/docs/handbook/declaration-merging.html#module-augmentation
Optional Catch Binding: A feature in TypeScript that allows the omission of the variable in a `catch` block if the error object is not used. Optional Catch Binding helps to reduce clutter in error handling when the error is not needed.
Override Keyword: A feature in TypeScript that ensures a subclass method is correctly overriding a method in its parent class. The Override Keyword provides explicit syntax to prevent accidental method redefinitions that do not match the parent class's signature.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-3.html#override-keyword
Keyof Operator with Generics: A feature that allows the `Keyof` operator to be used in combination with generics, enabling dynamic key access in a type-safe manner. Keyof Operator with Generics provides flexibility in working with object types while maintaining strong type checks.
https://www.typescriptlang.org/docs/handbook/2/keyof-types.html
Template Literal Types: A feature in TypeScript that allows developers to create types using string interpolation. Template Literal Types enable the combination of literal strings into more complex string types, providing greater flexibility in type definitions.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
Nominal Typing: A type-checking strategy that relies on explicit declarations of types, rather than structural compatibility. Nominal Typing can be simulated in TypeScript using techniques such as Branded Types to enforce type distinctions between otherwise structurally similar types.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#nominal-typing
Abstract Index Signatures: A feature in TypeScript that allows abstract classes or interfaces to define an index signature, enabling subclasses or implementing classes to provide specific index behavior while maintaining type safety. Abstract Index Signatures are useful for enforcing consistent indexing rules across multiple classes.
https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
In Operator: A type guard in TypeScript that checks if a property exists in an object. The In Operator allows for safe narrowing of types by verifying the existence of a property before accessing it, ensuring type safety during runtime checks.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#using-the-in-operator
Conditional Types with Infer: A feature in TypeScript that allows developers to infer types within a conditional type expression using the `infer` keyword. Conditional Types with Infer enables complex type transformations and ensures more precise type handling in generic scenarios.
Recursive Type Aliases: A feature that allows TypeScript type aliases to refer to themselves, enabling the representation of recursive data structures such as trees or nested arrays. Recursive Type Aliases help model complex, hierarchical data in a type-safe manner.
https://www.typescriptlang.org/docs/handbook/2/recursive-types.html
Template String Types: A feature in TypeScript that allows developers to define types using string templates, enabling type-safe string manipulation. Template String Types are useful for scenarios where the exact form of a string is critical, such as when constructing URLs or file paths.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
Readonly Index Signatures: A feature that ensures properties accessed through an index signature cannot be modified once they are set. Readonly Index Signatures are useful when working with objects or maps that should not allow reassignment of their values after creation.
https://www.typescriptlang.org/docs/handbook/interfaces.html#readonly-properties
Nominal Type Checking: A strategy in TypeScript for enforcing stricter type distinctions by associating unique tags with otherwise similar types. Nominal Type Checking helps prevent the accidental misuse of structurally compatible but semantically different types, such as distinguishing between units of measurement.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#nominal-typing
Utility Type – NonNullable: A Utility Type in TypeScript that constructs a type by excluding `null` and `undefined` from a given type. NonNullable ensures that a value can never be `null` or `undefined`, improving type safety in situations where these values are not permitted.
https://www.typescriptlang.org/docs/handbook/utility-types.html#nonnullabletype
Function Bivariance: A concept in TypeScript that allows function parameters to be less specific than the declared type, enabling greater flexibility in type assignment. Function Bivariance provides a way to assign functions to variables with broader parameter types without violating type safety.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html#function-parameter-bivariance
Global Augmentation: A technique in TypeScript that allows developers to modify or extend global objects or types, such as adding properties to the global `Window` object. Global Augmentation is useful for enhancing the behavior of built-in objects when working with browser or Node.js environments.
https://www.typescriptlang.org/docs/handbook/declaration-merging.html#global-augmentation
Type Compatibility: A key concept in TypeScript that ensures types are considered compatible if they share the same structure, even if they were defined separately. Type Compatibility relies on structural typing, allowing for flexible and reusable code by focusing on the shape of types rather than their names.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html
Type Guard: A feature in TypeScript that allows developers to narrow the type of a variable within a specific block of code, such as an `if` statement. Type Guards help ensure that certain operations are only performed on variables of specific types, improving type safety.
Mapped Types with Modifiers: A feature in TypeScript that allows developers to apply modifiers such as `readonly` or `optional` to the properties of a mapped type. Mapped Types with Modifiers offer greater flexibility in type transformations by enabling developers to modify the properties of existing types dynamically.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
TypeScript Declaration Files: Files with the `.d.ts` extension that provide type definitions for JavaScript libraries or code without TypeScript annotations. Declaration Files allow the TypeScript compiler to type-check code that interacts with untyped JavaScript code, improving safety in mixed-language projects.
https://www.typescriptlang.org/docs/handbook/declaration-files/introduction.html
Intersection Types with Conditional Logic: A feature in TypeScript that allows intersection types to be combined with conditional types, enabling more advanced type checks and transformations. Intersection Types with Conditional Logic ensure that all intersected types satisfy specific conditions for type compatibility.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types
TypeScript’s keyof with Objects: A feature that allows the `keyof` operator to extract the keys of an object type as a union of string literals. Keyof with Objects provides a way to create dynamic, type-safe relationships between the keys and values of object types.
https://www.typescriptlang.org/docs/handbook/2/keyof-types.html
Template Literals in Types: A feature in TypeScript that allows developers to create new types using string interpolation with literal types. Template Literals in Types enable the creation of complex string types, improving type safety when working with pattern-based string data.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
TypeScript Index Signatures for Dynamic Objects: A feature that allows object types to be defined with dynamic keys, enabling type-safe access to properties when the keys are not known at compile time. Index Signatures are especially useful for defining dictionary-like structures.
https://www.typescriptlang.org/docs/handbook/interfaces.html#index-signatures
TypeScript Variance: A concept in TypeScript that describes how subtypes relate to their parent types in function parameters and return types. Variance determines whether types can be safely replaced by their subtypes, allowing for more flexible type assignments while maintaining type safety.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html#variance
Generic Type Constraints: A feature in TypeScript that allows developers to restrict the types that can be passed as arguments to a generic function or class. Generic Type Constraints ensure that the type argument meets certain conditions, improving flexibility and safety when working with generics.
https://www.typescriptlang.org/docs/handbook/2/generics.html#generic-constraints
Nominal Typing with Branded Types: A pattern in TypeScript that enables nominal typing by adding a unique tag or “brand” to types, ensuring that types with the same structure but different meanings are not interchangeable. Branded Types help prevent errors by enforcing stronger distinctions between similar types.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#branded-types
Instance Type: A utility type in TypeScript that extracts the instance type from a class or constructor function. Instance Type allows developers to infer the type of objects created by a specific constructor, making it easier to work with class-based types dynamically.
https://www.typescriptlang.org/docs/handbook/utility-types.html#instancetype
Rest Parameters for TypeScript Functions: A feature that allows functions in TypeScript to accept an arbitrary number of arguments as an array. Rest Parameters provide flexibility when defining functions with a varying number of arguments, ensuring type safety for the parameters.
https://www.typescriptlang.org/docs/handbook/functions.html#rest-parameters
Generics with Multiple Constraints: A feature in TypeScript that allows generic type parameters to be constrained by multiple types using intersection types. Generics with Multiple Constraints ensure that the type argument satisfies all the specified conditions, increasing flexibility and type safety.
https://www.typescriptlang.org/docs/handbook/2/generics.html#generic-constraints
Optional Properties in Interfaces: A feature that allows properties in an interface to be marked as optional by appending a `?` symbol. Optional Properties provide flexibility in object structures, allowing certain properties to be omitted without causing type errors.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#optional-properties
Parameter Decorators: A feature in TypeScript that allows decorators to be applied to method parameters in classes. Parameter Decorators are commonly used in frameworks like Angular to inject dependencies or provide metadata for class methods.
https://www.typescriptlang.org/docs/handbook/decorators.html#parameter-decorators
Mapped Type Modifiers: A feature that allows developers to apply modifiers like `readonly` or `optional` to every property in a mapped type. Mapped Type Modifiers provide greater control when transforming object types, making it easier to create more flexible type definitions.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Recursive Conditional Types: A feature in TypeScript that allows conditional types to be defined recursively, enabling more complex type transformations. Recursive Conditional Types are useful for scenarios where a type depends on its own structure, such as with nested data.
https://www.typescriptlang.org/docs/handbook/2/recursive-types.html
Template Literal Types with Unions: A feature that allows TypeScript to combine string literal types with union types using string interpolation. Template Literal Types with Unions enable the creation of more complex types by concatenating multiple string literals dynamically.
https://www.typescriptlang.org/docs/handbook/2/template-literal-types.html
Infer Keyword in TypeScript: A keyword used within conditional types to infer the type of a variable from another type. The Infer Keyword enables more dynamic type manipulations by capturing types that are extracted during type evaluation.
Readonly Modifier for Function Parameters: A feature in TypeScript that ensures function parameters cannot be reassigned within the function body. The Readonly Modifier helps prevent accidental changes to parameter values and promotes immutability in function logic.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytype
Distributive Conditional Types: A feature in TypeScript where conditional types are applied across each member of a union type, distributing the condition over the union's elements. Distributive Conditional Types are useful for creating type transformations that need to handle union types precisely.
https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
ReturnType Utility Type: A utility type that extracts the return type of a function. The ReturnType type is useful for capturing the type of the value returned by a function, especially when working with functions that return complex types.
https://www.typescriptlang.org/docs/handbook/utility-types.html#returntypetype
Recursive Type Inference: A concept where TypeScript automatically infers types in recursive structures, such as trees or linked lists. Recursive Type Inference allows types to self-reference, making it possible to define data structures that recursively contain their own type.
https://www.typescriptlang.org/docs/handbook/2/recursive-types.html
TypeScript’s Pick Utility Type: A utility type that creates a new type by selecting specific properties from an existing type. Pick is useful when you need to create a smaller, focused type based on a subset of properties from a larger object type.
https://www.typescriptlang.org/docs/handbook/utility-types.html#picktype-keys
Omit Utility Type: A utility type in TypeScript that creates a new type by excluding one or more properties from an existing type. Omit is particularly useful for working with object types where certain properties are unnecessary for specific operations.
https://www.typescriptlang.org/docs/handbook/utility-types.html#omittype-keys
Union Type Narrowing: A feature in TypeScript where the type of a variable is narrowed from a broader union type to a more specific one based on runtime checks. Union Type Narrowing helps ensure that operations are only performed on valid types, reducing runtime errors.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#union-types
Intersection Types: A feature in TypeScript that combines multiple types into one, where the resulting type must satisfy all the constraints of the individual types. Intersection Types are useful for representing objects or values that need to meet multiple type requirements simultaneously.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types
ReadonlyArray Type: A type in TypeScript that represents an array that cannot be modified. The ReadonlyArray type ensures that once an array is created, its elements cannot be changed, promoting immutability in data structures.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlyarraytype
TypeScript’s Extract Utility Type: A utility type that constructs a new type by extracting a subset of types from a union type. The Extract utility type is useful when you need to filter out specific types from a union, ensuring that only the desired types are included.
https://www.typescriptlang.org/docs/handbook/utility-types.html#extracttype
Mapped Type Constraints: A feature in TypeScript that allows developers to restrict the keys of a mapped type to a specific subset using `keyof`. Mapped Type Constraints provide control over which keys in an object can be transformed, making it easier to work with specific properties in large types.
https://www.typescriptlang.org/docs/handbook/2/mapped-types.html
Instanceof Narrowing: A type guard in TypeScript that allows narrowing of a type using the `instanceof` operator. Instanceof Narrowing is particularly useful for distinguishing between different class instances and ensuring safe access to their properties and methods.
https://www.typescriptlang.org/docs/handbook/2/narrowing.html#using-instanceof
Parameter Properties: A shorthand in TypeScript that allows constructor parameters to be automatically declared and initialized as class properties. By prefixing constructor parameters with access modifiers (e.g., `public` or `private`), Parameter Properties reduce boilerplate code.
https://www.typescriptlang.org/docs/handbook/2/classes.html#parameter-properties
Indexed Access Types with Generics: A feature in TypeScript that allows dynamic access to types using generic keys. Indexed Access Types with Generics are useful for defining complex type relationships that depend on accessing the types of specific properties.
https://www.typescriptlang.org/docs/handbook/2/indexed-access-types.html
Optional Element in Tuple Types: A feature that allows tuple types to include optional elements. With Optional Elements in Tuple Types, developers can define tuples that have variable lengths, providing more flexibility while maintaining strict type safety for the defined elements.
https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-0.html#variadic-tuple-types
Optional Parameters in Functions: A feature that allows function parameters to be marked as optional by appending a `?` symbol. Optional Parameters in Functions enable more flexible function definitions, allowing callers to omit certain arguments without causing errors.
https://www.typescriptlang.org/docs/handbook/2/functions.html#optional-parameters
Decorators for Accessors: A feature in TypeScript that allows decorators to be applied to getter and setter methods of a class. Decorators for Accessors are used to modify or extend the behavior of property access, often adding metadata or validation logic.
https://www.typescriptlang.org/docs/handbook/decorators.html#accessor-decorators
Rest and Spread in TypeScript: A feature that allows arrays and objects to be expanded or collapsed using the rest (`…`) and spread operators. Rest and Spread are particularly useful for combining, copying, or separating arrays and objects while preserving immutability.
https://www.typescriptlang.org/docs/handbook/variable-declarations.html#spread
TypeScript’s Extract Utility Type with Generics: A utility type that allows developers to extract specific types from a generic union type. Extract with Generics is useful for filtering out only the relevant types from a complex union, ensuring type safety in more dynamic type systems.
https://www.typescriptlang.org/docs/handbook/utility-types.html#extracttype
TypeScript’s Required Utility Type: A utility type that makes all properties of a type required, reversing the behavior of optional properties. The Required Utility Type is helpful when working with partial types that need to be enforced as complete in certain contexts.
https://www.typescriptlang.org/docs/handbook/utility-types.html#requiredtype
This Parameter: A feature in TypeScript that allows developers to explicitly define the type of `this` within a function. This Parameter is useful in methods where the context of `this` can change, ensuring that the correct type is inferred for operations on `this`.
https://www.typescriptlang.org/docs/handbook/2/functions.html#this-parameters
Abstract Classes with Generics: A combination of Abstract Classes and Generics that allows abstract classes to define generic types. This enables Abstract Classes to be more flexible by allowing subclasses to provide specific types, making them useful for building reusable, type-safe class hierarchies.
https://www.typescriptlang.org/docs/handbook/2/generics.html#using-generics-in-classes
Literal Inference for Arrays: A feature in TypeScript where arrays created with `const` declarations can infer their element types as literals, preserving specific values. Literal Inference for Arrays ensures that array contents retain their precise types, rather than being widened to broader types like `string` or `number`.
https://www.typescriptlang.org/docs/handbook/2/everyday-types.html#literal-inference
Readonly Modifier for Tuple Types: A feature in TypeScript that allows tuple elements to be marked as immutable. Using the Readonly Modifier ensures that tuples cannot be modified after their creation, supporting immutability in data structures with fixed elements.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlytupletype
Default Generics: A feature that allows generic parameters to have default types. Default Generics are useful when a generic type needs to work with a default value if no type argument is provided, reducing the need for explicit type annotations in simple cases.
https://www.typescriptlang.org/docs/handbook/2/generics.html#default-type-parameters
Branded Types: A technique in TypeScript for adding additional information to primitive types, distinguishing between otherwise identical types. Branded Types are useful for enforcing stronger type distinctions in cases where multiple types share the same structure but have different meanings.
https://www.typescriptlang.org/docs/handbook/advanced-types.html#branded-types
Covariance and Contravariance: Concepts in TypeScript that describe how types can change in relation to their subtypes when used in function parameters and return values. Covariance allows a subtype to be used where a parent type is expected, while Contravariance allows a parent type in place of a subtype.
https://www.typescriptlang.org/docs/handbook/type-compatibility.html#covariance-and-contravariance
Utility Type – ReadonlyMap: A utility type that provides an immutable version of the standard Map type in TypeScript. ReadonlyMap ensures that once a map is created, neither its keys nor values can be modified, preserving data integrity.
https://www.typescriptlang.org/docs/handbook/utility-types.html#readonlymap
Overloaded Function Signatures: A feature that allows a function to have multiple call signatures in TypeScript. Overloaded Function Signatures enable functions to handle different parameter types or numbers of parameters while maintaining type safety for each variant.
https://www.typescriptlang.org/docs/handbook/functions.html#overloads
TypeScript’s Exclude Utility Type: A utility type that constructs a new type by excluding certain types from a union type. The Exclude Utility Type is useful when you want to filter out unwanted types from a union, leaving only the desired ones.
https://www.typescriptlang.org/docs/handbook/utility-types.html#excludetype-excluded
From Learning TypeScript by Josh Goldberg Glossary
- Ambient Context - TypeScript Ambient Context - “An area in code where you can declare types but cannot declare implementations. Generally used in reference to .d.ts declaration files.” (LrnTS 2022). See Also Declaration File
- Any - TypeScript Any - “any: a type that is allowed to be used anywhere and can be given anything. any can act as a top type, in that any type can be provided to a location of type any. Most of the time you probably want to use unknown for more accurate type safety.” (LrnTS 2022). See Also Unknown, Top Type
- Assignable, Assignability - TypeScript Assignable, TypeScript Assignability - “Whether one type is allowed to be used in place of another.” (LrnTS 2022)
- Billion Dollar Mistake]] - TypeScript Billion Dollar Mistake]] - “The catchy industry term for many type systems allowing values such as null to be used in places that require a different type. Coined by Tony Hoare in reference to the amount of damage it seems to have caused.” (LrnTS 2022). See Also Strict Null Checking
- Bottom Type - TypeScript Bottom Type - “A type that has no possible values — the empty set of types. No type is assignable to the bottom type. TypeScript provides the never keyword to indicate a bottom type.” (LrnTS 2022). See Also Never.
- Call Signature - TypeScript Call Signature - ”Type system description of how a function may be called. Includes a list of parameters and a return type.“ (LrnTS 2022)
- Cast, Type Cast - TypeScript Cast]], TypeScript Type Cast - “An assertion to TypeScript that a value is of a different type than what TypeScript would otherwise expect.” (LrnTS 2022)
- Class - TypeScript Class - ”JavaScript syntax sugar around functions that assign to a prototype. TypeScript allows working with JavaScript classes.“ (LrnTS 2022)
- Compile - TypeScript Compile - “Turn source code into another format. TypeScript includes a compiler that turns .ts/.tsx TypeScript source code into .js files.” (LrnTS 2022). See Also Transpile
- Conditional Type - TypeScript Conditional Type - “A type that resolves to one of two possible types, based on an existing type.” (LrnTS 2022)
- Const Assertion - TypeScript Const Assertion - “as const type assertion shorthand that tells TypeScript to use the most literal, readonly possible form of a value’s type.” (LrnTS 2022)
- Constituent, Constituent Type - TypeScript Constituent, TypeScript Constituent Type - “One of the types in an intersection or union type.” (LrnTS 2022)
- Declaration File - TypeScript Declaration File - “A file with the .d.ts extension. Declaration files create an ambient context, meaning they can only declare types and cannot declare implementations.” (LrnTS 2022). See Also Ambient Context
- Dynamically Typed, Dynamic Typing]] - TypeScript Dynamically Typed, TypeScript Dynamic Typing]] - “A classification of programming language that does not natively include a type checker. Examples of dynamically typed programming languages include JavaScript and Ruby.” (LrnTS 2022)
- DefinitelyTyped - TypeScript DefinitelyTyped - “The massive repository of community-authored type definitions for packages (DT for short). It contains thousands of .d.ts definitions along with automation around reviewing change proposals and publishing updates. Those definitions are published as packages under the @types/ organization on npm, such as @types/react.” (LrnTS 2022)
- Discriminant - TypeScript Discriminant]] - “The member of a discriminated union that has the same name but different value in each constituent type. In type Color = { result: string, status: 0 } | { error: Error, status: 1 }, the status member acts as the discriminant.” (LrnTS 2022)
- Discriminated Union, Discriminated Type Union - TypeScript Discriminated Union, TypeScript Discriminated Type Union - “A union of types where a “discriminant” member exists with the same name but different value in each constituent type. Checking the value of the discriminant acts as a form of type narrowing.” (LrnTS 2022)
- Distributivity - TypeScript Distributivity]] - “A property of TypeScript’s conditional types when given union template types: meaning their resultant type will be a union of applying that conditional type to each of the constituents (types in the union type). In other words, ConditionalType<T | U> is the same as Conditional<T> | Conditional<U>.” (LrnTS 2022)
- Duck [[Typed - TypeScript Duck Typed - “A common phrase for how JavaScript’s type system behaves. It comes from the phrase “if it looks like a duck and quacks like a duck, it’s probably a duck”. It means that JavaScript allows any value to be passed anywhere; if an object is asked for a member that doesn’t exist, the result will be undefined.” (LrnTS 2022). See Also Structurally Typed
- Emit, Emitted [[Code - TypeScript Emit]], TypeScript Emitted Code - “The output from a compiler, such as .js files often produced by running tsc. The TypeScript compiler’s JavaScript and/or definition file emits can be controlled by its compiler options.” (LrnTS 2022)
- Enum - TypeScript Enum]] - “A set of literal values stored in an object with a friendly name for each value. Enums are a rare example of TypeScript-specific syntax extension to vanilla JavaScript.” (LrnTS 2022)
- Evolving Any - TypeScript Evolving Any]] - “A special case of implicit any for variables who don’t have a type annotation or initial value. Their type will be evolved to whatever they are used with.” (LrnTS 2022). See Also Implicit Any
- Function Overload, Over[[loaded Function - TypeScript Function Overload, TypeScript Overloaded Function - “A way to describe a function able to be called with drastically different sets of parameters.” (LrnTS 2022)
- IDE, Integrated [[Development Environment - TypeScript IDE, TypeScript Integrated Development Environment - ”Program that provides developer tooling on top of a text editor for source code. IDEs generally come with debuggers, syntax highlighting, and plugins that surface complaints from programming languages such as type errors. This book uses VS Code for its IDE examples but others include Atom, Emacs, Vim, Visual Studio, and WebStorm.“ (LrnTS 2022)
- Implementation Signature - TypeScript Implementation Signature - “The final signature declared on an overloaded function, used for its implementation’s parameters.” (LrnTS 2022). See Also Function Overload
- Implicit Any - TypeScript Implicit Any]] - “When TypeScript cannot immediately deduce the type of a class property, function parameter, or variable, it implicitly assumes the type to be any. Implicit any types for class properties and function parameters may be configured to be type errors using the noImplicitAny compiler option.” (LrnTS 2022)
- Interface Merging - TypeScript Interface Merging - “A property of interfaces that when multiple with the same name are declared in the same scope, they combine into one interface instead of causing a type error about conflicting names. This is most commonly used by definition authors to augment global interfaces such as Window.” (LrnTS 2022)
- Inter[[section Type - TypeScript Intersection Type - “A type that uses the & operator to indicate it has all the properties of both its constituents.” (LrnTS 2022)
- Module Resolution - TypeScript Module Resolution - “The set of steps used to determine what file a module import resolves to. The TypeScript compiler can have this specified by its moduleResolution compiler option.” (LrnTS 2022)
- Namespace]] - TypeScript Namespace]] - “An old construct in TypeScript that creates a globally available object with “exported” contents available to call as members of that object. Namespaces are a rare example of TypeScript-specific syntax extension to vanilla JavaScript. These days they’re mostly used in .d.ts declaration files.” (LrnTS 2022)
- never - TypeScript never]] - “The TypeScript type representing the bottom type: a type that can have no possible values.” (LrnTS 2022). See Also Bottom Type.
- Non-[[Null Assertion - TypeScript Non-Null Assertion - “A shorthand ! that asserts a type is not null or undefined.” (LrnTS 2022)
- Optional - TypeScript Optional - “A function parameter, class property, or member of an interface or object type that doesn’t need to be provided. Indicated by placing a ? after its name, or for function parameters and class properties, alternately by providing a default value with a =.” (LrnTS 2022)
- Parameter Property - TypeScript Parameter Property - “A TypeScript syntax extension for declaring a property assigned to a member property of the same type at the beginning of a class constructor.” (LrnTS 2022)
- Pascal Case - TypeScript Pascal Case - “A naming convention where the first letter of each compound word in a name is capitalized, like PascalCase. The convention for names of many TypeScript type system constructs, including generics, interfaces, and type aliases.” (LrnTS 2022)
- Project References]] - TypeScript Project References]] - “A feature of TypeScript configuration files where they can reference other configuration files’ projects as dependencies. This allows you to use TypeScript as a build coordinator to enforce a project dependency tree.” (LrnTS 2022)
- Return Type - TypeScript Return Type - “The type that must be returned by a function. If multiple return statements exist in the function with different types, it will be a union of all those possible types. If the function cannot possibly return, it will be never.” (LrnTS 2022)
- Script - TypeScript Script - “Any source code file that is not a module.” (LrnTS 2022). See Also Module.
- Strict Mode - TypeScript Strict Mode - “A collection of compiler options that increase the amount of strictness and number of checks the TypeScript type checker performs. This can be enabled for tsc with the –strict flag and in TSConfiguration files with the ”strict”: true compilerOption.“ (LrnTS 2022)
- Strict Null Checking - TypeScript Strict Null Checking - “A strict mode for TypeScript where null and undefined are no longer allowed to be provided to types that don’t explicitly include them.” (LrnTS 2022). See Also Billion Dollar Mistake]]
- Structurally Typed - TypeScript Structurally Typed - “A type system where any value that happens to satisfy a type is allowed to be used as an instance of that type.” (LrnTS 2022). See Also Duck [[Typed
- Target - TypeScript Target - “The TypeScript compiler option to specify how far back in syntax support JavaScript code needs to be transpiled, such as es5 or es2017. Although target defaults to es3 for backwards compatibility reasons, it’s advisable use as new JavaScript syntax as possible per your target platform(s), as supporting newer JavaScript features in older environments necessitates creating more JavaScript code.” (LrnTS 2022)
- Transpile - TypeScript Transpile - “A term for compilation that turns source code from one human-readable programming language into another. TypeScript includes a compiler that turns .ts/.tsx TypeScript source code into .js files, which is sometimes referred to as transpilation.” (LrnTS 2022). See Also Compile
- Type Annotation - TypeScript Type Annotation - “An annotation after a name used to indicate its type. Consists of `: ` and the name of a type.” (LrnTS 2022)
- Type system - TypeScript Type system - “The set of rules for how a programming language understands what types the constructs in a program may have.” (LrnTS 2022)
- Union - TypeScript Union - “A type describing a value that can be two or more possible types. Represented by the | pipe between each possible type.” (LrnTS 2022)
- Visibility - TypeScript Visibility]] - “Specifying whether a class member is visible to code outside the class. Indicated before the member’s declaration with the public, protected, and private keywords. Visibility and its keywords predate JavaScript’s true # member privacy and exist only in the TypeScript type system.” (LrnTS 2022). See Also Privacy.
- Void - [[TypeScript Void - “A type indicating the lack of returned value from a function, represented by the void keyword in TypeScript. Functions are thought of as returning void if they have no return statements that return a value.” (LrnTS 2022)
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- In part excerpted from Learning TypeScript by Josh Goldberg Glossary
TypeScript Vocabulary List (Sorted by Popularity)
TypeScript Programming Language, TypeScript Compiler, TypeScript tsc Command, TypeScript Transpilation, TypeScript Type Annotation, TypeScript Interface, TypeScript Type Alias, TypeScript Enum, TypeScript Class, TypeScript Module, TypeScript Namespace, TypeScript Ambient Declaration, TypeScript d.ts File, TypeScript Declaration File, TypeScript tsconfig.json, TypeScript Strict Mode, TypeScript Strict Null Checks, TypeScript Non-Null Assertion Operator, TypeScript Type Inference, TypeScript Union Type, TypeScript Intersection Type, TypeScript Generics, TypeScript Generic Constraints, TypeScript Generic Default Type, TypeScript Partial Type, TypeScript Readonly Type, TypeScript Pick Type, TypeScript Omit Type, TypeScript Exclude Type, TypeScript Extract Type, TypeScript Record Type, TypeScript ReturnType Type, TypeScript Parameters Type, TypeScript ConstructorParameters Type, TypeScript InstanceType Type, TypeScript Required Type, TypeScript NonNullable Type, TypeScript ThisType, TypeScript Unknown Type, TypeScript Never Type, TypeScript Any Type, TypeScript Void Type, TypeScript Object Type, TypeScript Symbol Type, TypeScript Literal Type, TypeScript Template Literal Type, TypeScript Indexed Access Type, TypeScript Conditional Type, TypeScript Infer Keyword, TypeScript Mapped Type, TypeScript Keyof Keyword, TypeScript In Keyword (Types), TypeScript Extends Keyword (Types), TypeScript Structural Typing, TypeScript Duck Typing, TypeScript Nominal Typing (via branding), TypeScript Interface Merging, TypeScript Declaration Merging, TypeScript Module Augmentation, TypeScript Ambient Module, TypeScript Triple-Slash Directive, TypeScript Reference Path, TypeScript Reference Types, TypeScript Reference Lib, TypeScript Reference NoDefaultLib, TypeScript JSX, TypeScript TSX, TypeScript React JSX, TypeScript JSX.Element, TypeScript JSX.IntrinsicElements, TypeScript JSX.ElementClass, TypeScript Decorator, TypeScript Experimental Decorators, TypeScript Metadata Reflection API, TypeScript EmitDecoratorMetadata, TypeScript Decorator Factory, TypeScript Class Decorator, TypeScript Method Decorator, TypeScript Property Decorator, TypeScript Parameter Decorator, TypeScript Accessor Decorator, TypeScript Abstract Class, TypeScript Public Keyword, TypeScript Private Keyword, TypeScript Protected Keyword, TypeScript Readonly Keyword, TypeScript Static Keyword, TypeScript Implements Keyword, TypeScript Extends Keyword (Classes), TypeScript Super Keyword, TypeScript Constructor Parameter Properties, TypeScript Access Modifiers, TypeScript Index Signature, TypeScript Optional Chaining Operator, TypeScript Nullish Coalescing Operator, TypeScript Assertion Function, TypeScript Assertion Signature, TypeScript Type Assertion, TypeScript as Keyword, TypeScript Angle Bracket Assertion (Older Syntax), TypeScript Definite Assignment Assertion, TypeScript Discriminated Union, TypeScript Tagged Union, TypeScript Branded Type, TypeScript Intersection Property Distribution, TypeScript Function Type, TypeScript Call Signature, TypeScript Construct Signature, TypeScript Overloaded Function, TypeScript Rest Parameters, TypeScript Default Parameters, TypeScript Arrow Function Type, TypeScript Void Return Type, TypeScript Unknown Return Type, TypeScript Promise Type, TypeScript Async Function Type, TypeScript Awaited Type, TypeScript Generator Type, TypeScript Iterator Type, TypeScript Iterable Type, TypeScript IterableIterator Type, TypeScript AsyncIterable Type, TypeScript AsyncIterator Type, TypeScript AsyncIterableIterator Type, TypeScript Symbol.iterator, TypeScript Symbol.asyncIterator, TypeScript Symbol.hasInstance, TypeScript Symbol.species, TypeScript Symbol.toPrimitive, TypeScript Symbol.toStringTag, TypeScript Interface Inheritance, TypeScript Extending Interface, TypeScript Implementing Interface, TypeScript Hybrid Types, TypeScript Callable Interface, TypeScript Newable Interface, TypeScript Class Expression, TypeScript Abstract Method, TypeScript Abstract Property, TypeScript Abstract Constructor, TypeScript Class Fields, TypeScript Parameter Decorators, TypeScript Reflect Metadata, TypeScript JSDoc Annotations, TypeScript @type JSDoc Tag, TypeScript @typedef JSDoc Tag, TypeScript @template JSDoc Tag, TypeScript @param JSDoc Tag, TypeScript @returns JSDoc Tag, TypeScript StrictBindCallApply, TypeScript StrictFunctionTypes, TypeScript StrictPropertyInitialization, TypeScript StrictNullChecks Flag, TypeScript NoImplicitAny, TypeScript NoImplicitThis, TypeScript AlwaysStrict, TypeScript NoUnusedLocals, TypeScript NoUnusedParameters, TypeScript NoImplicitReturns, TypeScript NoFallthroughCasesInSwitch, TypeScript StrictUnknownChecks, TypeScript StrictBindCallApply, TypeScript NoImplicitOverride, TypeScript UseUnknownInCatchVariables, TypeScript ImportsNotUsedAsValues, TypeScript IsolatedModules, TypeScript PreserveSymlinks, TypeScript BaseUrl, TypeScript Paths Mapping, TypeScript RootDirs, TypeScript Composite Projects, TypeScript Build Mode, TypeScript Incremental Compilation, TypeScript DeclarationMap, TypeScript SourceMap, TypeScript InlineSourceMap, TypeScript InlineSources, TypeScript RemoveComments, TypeScript NoEmit, TypeScript NoEmitOnError, TypeScript OutDir, TypeScript OutFile, TypeScript RootDir, TypeScript TsBuildInfoFile, TypeScript DeclarationDir, TypeScript ListFiles, TypeScript ListEmittedFiles, TypeScript Extended Diagnostics, TypeScript Diagnostics, TypeScript TraceResolution, TypeScript ExplainFiles, TypeScript StripInternal, TypeScript StrictOptionCheck, TypeScript StrictModeFlags, TypeScript Syntactic Diagnostics, TypeScript Semantic Diagnostics, TypeScript Declaration Diagnostics, TypeScript PseudoBigInt, TypeScript Bigint Literal, TypeScript Bigint Type, TypeScript IntrinsicAttributes, TypeScript IntrinsicClassAttributes, TypeScript IntrinsicElements, TypeScript Global Augmentation, TypeScript Shorthand Ambient Module, TypeScript Export As Namespace, TypeScript Export =, TypeScript Import = require, TypeScript Type-Only Imports, TypeScript Type-Only Exports, TypeScript Export Type, TypeScript Import Type, TypeScript typeof Type Operator, TypeScript keyof Type Operator, TypeScript unique symbol, TypeScript Template Literal Type Inference, TypeScript Variadic Tuple Types, TypeScript Labeled Tuple Elements, TypeScript Template Literal Type, TypeScript Template Literal String, TypeScript Indexed Access Types, TypeScript Conditional Types Extended, TypeScript Distributed Conditional Types, TypeScript Recursive Conditional Types, TypeScript Tail Recursion Elimination, TypeScript Type Guards, TypeScript User-Defined Type Guard, TypeScript in Type Guards, TypeScript instanceof Type Guards, TypeScript typeof Type Guards, TypeScript Assertion Signatures, TypeScript Definite Assignment Assertions, TypeScript Control Flow Analysis, TypeScript Control Flow Based Type Analysis, TypeScript Control Flow Graph, TypeScript Flow Nodes, TypeScript Narrowing, TypeScript Type Predicates, TypeScript Function Overloads, TypeScript Declaration Emit, TypeScript Declaration Transformation, TypeScript Symbol Table, TypeScript Binder, TypeScript Checker, TypeScript Emitter, TypeScript Transformer, TypeScript Compiler Host, TypeScript Language Service, TypeScript Compiler API, TypeScript AST (Abstract Syntax Tree), TypeScript Node Interface, TypeScript SourceFile, TypeScript SyntaxKind Enum, TypeScript Checker API, TypeScript Program API, TypeScript TypeChecker API, TypeScript CompilerOptions Interface, TypeScript CompilerOptions Diagnostics, TypeScript ProjectReferences, TypeScript Composite Flag, TypeScript Declaration Flag, TypeScript Incremental Flag, TypeScript TSBuildInfo File, TypeScript watch Mode, TypeScript watchFile, TypeScript watchDirectory, TypeScript createProgram, TypeScript createWatchProgram, TypeScript createIncrementalProgram, TypeScript createSolutionBuilder, TypeScript createSolutionBuilderWithWatch, TypeScript resolveModuleName, TypeScript resolveTypeReferenceDirective, TypeScript Custom Module Resolution, TypeScript Plugin API, TypeScript Compiler Plugin, TypeScript Language Service Plugin, TypeScript CompletionInfo, TypeScript CompletionEntry, TypeScript SignatureHelp, TypeScript QuickInfo, TypeScript DefinitionInfo, TypeScript ImplementationInfo, TypeScript CodeFixAction, TypeScript CodeFix, TypeScript RefactorInfo, TypeScript RefactorActionInfo, TypeScript NavigationBarItem, TypeScript NavigationTree, TypeScript RenameInfo, TypeScript RenameLocations, TypeScript FormattingOptions, TypeScript TextChange, TypeScript EditorSettings, TypeScript UserPreferences, TypeScript CompilerHost.getSourceFile, TypeScript CompilerHost.getDefaultLibFileName, TypeScript CompilerHost.writeFile, TypeScript resolveModuleNames Hook, TypeScript resolveTypeReferenceDirectives Hook, TypeScript writeFile Callback, TypeScript CustomTransformers, TypeScript TransformerFactory, TypeScript TransformerContext, TypeScript Visitor Function, TypeScript updateSourceFileNode, TypeScript updateNode, TypeScript Printer API, TypeScript createPrinter, TypeScript PrintHandlers, TypeScript PrintFile, TypeScript Type Format Flags, TypeScript Symbol Display Builder, TypeScript TypeToString, TypeScript SymbolToString, TypeScript Diagnostic Message, TypeScript Diagnostic Category, TypeScript Diagnostic Code, TypeScript DiagnosticRelatedInformation, TypeScript DiagnosticReporter, TypeScript EmitResult, TypeScript PreEmitDiagnostics, TypeScript SyntacticDiagnostics, TypeScript SemanticDiagnostics, TypeScript DeclarationDiagnostics, TypeScript getParsedCommandLineOfConfigFile, TypeScript parseJsonConfigFileContent, TypeScript convertCompilerOptionsFromJson, TypeScript resolveProjectReferencePath, TypeScript getAllProjectReferences, TypeScript LanguageServer Protocol Integration, TypeScript tsserver, TypeScript tsserverlibrary, TypeScript tsserver API, TypeScript tsserverplugin, TypeScript Editor Integration, TypeScript Sublime Text Integration, TypeScript VSCode Integration, TypeScript WebStorm Integration, TypeScript Eclipse Integration, TypeScript Vim Integration, TypeScript Emacs Integration, TypeScript Atom Integration, TypeScript Monaco Editor Integration, TypeScript Playground, TypeScript REPL Tools, TypeScript Node Integration, TypeScript Deno Integration, TypeScript Babel Integration, TypeScript Webpack Loader, TypeScript Rollup Plugin, TypeScript Parcel Integration, TypeScript FuseBox Integration, TypeScript Gulp Integration, TypeScript Grunt Integration, TypeScript ESLint Integration, TypeScript TSLint (Deprecated), TypeScript Prettier Integration, TypeScript Formatter, TypeScript Linter, TypeScript Language Server, TypeScript Server Plugin, TypeScript Vue SFC Integration, TypeScript Angular Integration, TypeScript React Integration, TypeScript JSX Mode, TypeScript TSX Mode, TypeScript Next.js Integration, TypeScript Gatsby Integration, TypeScript Nuxt.js Integration, TypeScript Svelte Integration, TypeScript Stencil Integration, TypeScript LitElement Integration, TypeScript Polymer Integration, TypeScript RxJS Type Definitions, TypeScript Node Type Definitions, TypeScript DOM Type Definitions, TypeScript ESNext Type Definitions, TypeScript ES2015 Type Definitions, TypeScript ES2017 Type Definitions, TypeScript ES2020 Type Definitions, TypeScript ES2021 Type Definitions, TypeScript ES2022 Type Definitions, TypeScript ES3 Compatibility, TypeScript ES5 Target, TypeScript ES6 Target, TypeScript ES2015 Target, TypeScript ES2017 Target, TypeScript ES2018 Target, TypeScript ES2019 Target, TypeScript ES2020 Target, TypeScript ES2021 Target, TypeScript ES2022 Target, TypeScript ESNext Target, TypeScript Module CommonJS, TypeScript Module AMD, TypeScript Module UMD, TypeScript Module SystemJS, TypeScript Module ESNext, TypeScript Module NodeNext, TypeScript Module Node16, TypeScript Lib ES5, TypeScript Lib ES6, TypeScript Lib ES2015, TypeScript Lib ES2016, TypeScript Lib ES2017, TypeScript Lib ES2018, TypeScript Lib ES2019, TypeScript Lib ES2020, TypeScript Lib ES2021, TypeScript Lib ES2022, TypeScript Lib DOM, TypeScript Lib Webworker, TypeScript Lib Webworker.Iterable, TypeScript Lib ScriptHost, TypeScript Lib DOM.Iterable, TypeScript Lib ESNext, TypeScript Target Option, TypeScript ModuleResolutionOption, TypeScript BaseUrl Option, TypeScript RootDirs Option, TypeScript Paths Option, TypeScript TypeRoots Option, TypeScript Types Option, TypeScript TraceResolution Option, TypeScript PreserveSymlinks Option, TypeScript AllowJs, TypeScript CheckJs, TypeScript Declaration, TypeScript DeclarationMap, TypeScript RemoveComments, TypeScript Incremental, TypeScript Composite, TypeScript InlineSourceMap, TypeScript InlineSources, TypeScript SourceMap, TypeScript IsolatedModules, TypeScript SkipLibCheck, TypeScript SkipDefaultLibCheck, TypeScript ForceConsistentCasingInFileNames, TypeScript RootDir, TypeScript OutDir, TypeScript OutFile, TypeScript AllowSyntheticDefaultImports, TypeScript ExperimentalDecorators, TypeScript EmitDecoratorMetadata, TypeScript DownlevelIteration, TypeScript StrictBindCallApply Option, TypeScript StrictPropertyInitialization Option, TypeScript UseUnknownInCatchVariables Option, TypeScript ImportsNotUsedAsValues Option, TypeScript PreserveConstEnums, TypeScript NoEmit, TypeScript NoEmitOnError, TypeScript ImportHelpers, TypeScript IsolatedModules Option, TypeScript Babel Plugin Transform TypeScript, TypeScript TypeDoc Integration, TypeScript API Extractor Integration, TypeScript Source Maps Support, TypeScript Decorators Metadata, TypeScript Experimental Flags, TypeScript Constraint Satisfaction, TypeScript Indexed Access Update, TypeScript Watch Mode Iteration, TypeScript watchFile Strategy, TypeScript watchDirectory Strategy, TypeScript incremental compilation cache, TypeScript composite build mode, TypeScript build reference, TypeScript output chunking, TypeScript declaration bundling, TypeScript path mapping resolution, TypeScript module specifier resolution, TypeScript import elision, TypeScript JSX factory, TypeScript JSX fragment factory, TypeScript JSX runtime, TypeScript preserve JSX, TypeScript react-jsx mode, TypeScript react-jsxdev mode, TypeScript isolated JSX namespace, TypeScript intrinsic element attribute types, TypeScript union type narrowing, TypeScript control flow narrowing, TypeScript discriminant property checks, TypeScript exhaustive switch checks, TypeScript unreachable code detection, TypeScript definite assignment checks, TypeScript optional property checks, TypeScript template literal type inference, TypeScript partial inference in generic, TypeScript tuple type inference, TypeScript tuple variance, TypeScript mapped type modifiers, TypeScript template literal type patterns, TypeScript conditional type inference patterns, TypeScript recursive type references, TypeScript tail-call optimization in types, TypeScript big integer literal types, TypeScript symbol literal types, TypeScript unique symbol types, TypeScript indexed access constraints, TypeScript type compatibility rules, TypeScript subtype and assignability, TypeScript assignability checks, TypeScript structural typing rules, TypeScript type alias circular references, TypeScript limit on instantiation depth, TypeScript error message hints, TypeScript suggestion diagnostics, TypeScript code actions, TypeScript refactorings, TypeScript organize imports, TypeScript rename symbol, TypeScript code fix all, TypeScript diagnostic tags, TypeScript unreachable code is error, TypeScript deprecated API warnings, TypeScript quick fixes for missed imports, TypeScript auto import suggestions, TypeScript auto fix on save, TypeScript incremental build watch, TypeScript composite project references, TypeScript solution style tsconfig, TypeScript project graph, TypeScript project dependency, TypeScript build order, TypeScript outDir redirect, TypeScript preserve watch output order, TypeScript advanced module resolution tracing, TypeScript plugin config in tsconfig, TypeScript plugin diagnostics, TypeScript plugin extra file extensions, TypeScript plugin language service extension, TypeScript server high memory usage, TypeScript server performance tracing, TypeScript server logVerbosity, TypeScript server cancellation tokens, TypeScript language server protocol features, TypeScript auto import from inferred project, TypeScript auto @ts-check in JS, TypeScript checkJs mode, TypeScript allowJs mode, TypeScript declaration and allowJs, TypeScript composite and allowJs, TypeScript incremental and composite flags
TypeScript: TypeScript Glossary, TypeScript Best Practices, Web Development Best Practices, JavaScript Best Practices, TypeScript Fundamentals, TypeScript Inventor - TypeScript Language Designer: Anders Hejlsberg of Microsoft on October 1, 2012; TypeScript Keywords, TypeScript Built-In Data Types, TypeScript Data Structures - TypeScript Algorithms, TypeScript Syntax, TypeScript on Linux, TypeScript on macOS, TypeScript on Windows, TypeScript on Android, TypeScript on iOS, TypeScript Installation, TypeScript Containerization (TypeScript with Docker, TypeScript with Podman, TypeScript and Kubernetes), TypeScript OOP - TypeScript Design Patterns, Clean TypeScript - TypeScript Style Guide, TypeScript Best Practices - TypeScript BDD, Web Browser, Web Development, HTML-CSS, TypeScript Frameworks (Angular), JavaScript Libraries (React.js with TypeScript, Vue.js with TypeScript, jQuery with TypeScript), TypeScript on the Server (TypeScript with Node.js, TypeScript with Deno, TypeScript with Express.js), TypeScript Compiler (tsc, tsconfig.json), TypeScript Transpiler (Transpile TypeScript into JavaScript), Babel and TypeScript, TypeScript Package Management, NPM and TypeScript, NVM and TypeScript, Yarn Package Manager and TypeScript, TypeScript IDEs (Visual Studio Code, Visual Studio, JetBrains WebStorm), TypeScript Development Tools, TypeScript Linter, TypeScript Debugging (Chrome DevTools, JavaScript Source Maps), TypeScript Testing (TypeScript TDD, Selenium, Jest, Mocha.js, Jasmine, Tape Testing (tap-producing test harness for Node.js and browsers), Supertest, React Testing Library, Enzyme.js React Testing, Angular TestBed), TypeScript DevOps - TypeScript SRE, TypeScript Data Science - TypeScript DataOps, TypeScript Machine Learning, TypeScript Deep Learning, Functional TypeScript, TypeScript Concurrency (WebAssembly - WASM) - TypeScript Async (TypeScript Await, TypeScript Promises, TypeScript Workers - Web Workers, Service Workers, Browser Main Thread), TypeScript Concurrency, TypeScript History, TypeScript Bibliography, Manning TypeScript Series, TypeScript Glossary - Glossaire de TypeScript - French, TypeScript T, TypeScript Courses, TypeScript Standard Library, TypeScript Libraries, TypeScript Frameworks (Angular), TypeScript Research, JavaScript, TypeScript GitHub, Written in TypeScript, TypeScript Popularity, TypeScript Awesome, TypeScript Versions. (navbar_typescript - see also navbar_javascript, navbar_typescript_networking, navbar_javascript_libraries, navbar_typescript_libraries, navbar_typescript_versions, navbar_typescript_standard_library, navbar_typescript_libraries, navbar_typescript_reserved_words, navbar_typescript_functional, navbar_typescript_concurrency, navbar_typescript_async, navbar_javascript_standard_library, navbar_react.js, navbar_angular, navbar_vue, navbar_javascript_standard_library, navbar_web_development)
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