https://DevOpsCloud.io -- Cloud Monk Losang Jinpa

Return to Standard Library, JavaScript, JavaScript Libraries

See: core-js

• JavaScript Standard Libraries

Return to Full-Stack Web Development, Full-Stack Developer, JavaScript Standard Library Glossary, JavaScript Standard Library Topics

JavaScript Standard Library

The JavaScript Standard Library, an integral part of the JavaScript programming language, provides a collection of built-in objects and functions designed to assist with common programming tasks. This library includes objects and functions for handling arrays, dates, math computations, and more, facilitating easier and more efficient coding practices. Although JavaScript itself was created by Brendan Eich in 1995, the standard library has evolved significantly over the years, especially with updates in ECMAScript standards, to include a broader range of functionalities that support modern web development.

Over time, the JavaScript Standard Library has expanded with each update to the ECMAScript standard, the most recent of which include ECMAScript 2020 and ECMAScript 2021. These updates have introduced features such as big integers, dynamic imports, and various new methods for existing prototypes like Array, String, and Object, which enhance the capability to handle data and perform complex operations. The standard library's development is overseen by ECMA International, with the goal of maintaining JavaScript's position as a versatile and powerful language for both client-side and server-side applications.

JavaScript Standard Library

The JavaScript Standard Library is a critical component of the JavaScript language, providing built-in objects and functions that simplify common programming tasks. JavaScript itself was created by Brendan Eich in 1995 as part of the development of the Netscape Navigator browser. The standard library has grown significantly since its inception, paralleling the evolution of JavaScript from a scripting tool for browsers to a robust language capable of handling complex applications on both the client and server sides.

The standard library's development is closely tied to the evolution of the ECMAScript standard, which is the scripting language specification that JavaScript implements. Managed by ECMA International, this standard first emerged in 1997 and has undergone numerous revisions to include more features and capabilities in the standard library. Each iteration of ECMAScript brings enhancements that are integrated into the JavaScript Standard Library, ensuring the language stays relevant and powerful.

Over the years, significant improvements have been made to the Array and String objects in the JavaScript Standard Library. These enhancements include methods for searching, manipulating, and iterating over arrays and strings, which have streamlined the way developers can handle data structures without the need for external libraries. Functions like `Array.prototype.map()` and `String.prototype.includes()` are examples of such advancements.

The Object and Function objects have also received updates that enhance their utility in application development. New methods for object manipulation, such as `Object.assign()` and `Object.entries()`, have made it easier to interact with objects and perform operations that were previously more cumbersome or less performance-efficient. Similarly, updates to function handling, including arrow functions introduced in ECMAScript 2015, have simplified function expressions and improved lexical scoping.

The Number and Math objects in the standard library have been expanded to include features that support more complex mathematical calculations and number formats. This includes the introduction of `Math.pow()` for exponentiation, and `Number.isInteger()`, which are indispensable for financial and scientific applications that require high precision and complex computations.

Improvements to the Date object have addressed many of the original limitations related to date and time manipulation in JavaScript. New methods and better timezone handling have significantly eased the development of applications that require dynamic, locale-aware date functions. These changes have made JavaScript a more viable option for applications like calendaring apps and scheduling systems.

The integration of JSON (JavaScript Object Notation) as a native part of the JavaScript Standard Library has been pivotal. Since ECMAScript 5 in 2009, methods such as `JSON.parse()` and `JSON.stringify()` have become standard tools for data interchange on the web, reflecting JavaScript's critical role in modern web development.

Regular expressions have seen enhancements that make pattern matching more robust in JavaScript. Features like sticky matching and additional flags have broadened the capabilities of RegExp objects, allowing for more complex and efficient text processing and validation tasks.

Global objects such as `Infinity`, `NaN`, and `undefined` have been standardized to provide foundational elements that support the basic functionality of the language. Their consistent behavior across different JavaScript environments ensures that fundamental aspects of language behavior remain reliable and predictable.

Error handling in JavaScript has been standardized through objects like `Error`, `TypeError`, and `SyntaxError`. These enhancements facilitate more sophisticated error detection and handling mechanisms, allowing developers to build more robust and user-friendly applications.

With the introduction of Promises in ECMAScript 2015, the standard library has embraced asynchronous programming, a critical feature for handling operations like network requests without blocking the main execution thread. This development has been fundamental in supporting the modern, event-driven style of programming prevalent in Node.js and browser-based applications.

Iterators and generators were added to facilitate more efficient handling of collections and to support new looping constructs. These features enable better control over iteration processes and lazy evaluation, which are essential for performance-critical applications and for managing large datasets.

The standardization of modules in ECMAScript 2015 and the introduction of import/export syntax have revolutionized the structure and organization of JavaScript code. This modular approach has improved code manageability, reuse, and encapsulation, aligning JavaScript with more traditional programming languages in terms of application architecture.

The ongoing development of the JavaScript Standard Library is focused

on addressing the needs of a growingly diverse development community and the expanding role of [[JavaScript]] in technology. Future revisions of the [[ECMAScript]] standard will continue to refine and introduce features that enhance the efficiency, security, and usability of [[JavaScript]] across various platforms.

JavaScript Standard Library Alternatives - Alternatives to JavaScript Standard Library

While the JavaScript Standard Library provides a robust foundation for web and application development, certain projects may require functionality beyond what is natively offered. Developers often turn to alternative libraries and frameworks that extend or enhance the capabilities of JavaScript with additional utilities, functions, and syntactic sugar. These alternatives can offer more specific or optimized solutions for data handling, user interface development, and asynchronous programming.

Lodash and Underscore.js are two of the most popular utility libraries that serve as alternatives to the JavaScript Standard Library. Both provide a wide range of helpful functions that simplify tasks such as array manipulation, object handling, and function debouncing. These libraries are particularly favored for their methods that streamline the more verbose operations in JavaScript, offering a cleaner and more intuitive syntax for complex data manipulation and iteration.

For developers focused on functional programming, Ramda offers a suite of tools that emphasize a functional approach, which is different from the more traditional imperative style native to JavaScript. Ramda provides immutability and side-effect free functions, which help in creating more predictable code. It includes utilities for composing functions, managing side effects, and handling data transformations, which make it a strong alternative for projects where functional programming paradigms are preferred.

jQuery was once the de facto standard for simplifying DOM (Document Object Model) manipulation, event handling, and AJAX calls in JavaScript. Although modern JavaScript has significantly reduced the need for jQuery with updated DOM manipulation methods and fetch API, jQuery still remains a viable alternative for older projects that need to maintain compatibility with legacy browsers or where developers prefer its concise syntax for DOM operations.

Modern development frameworks like React, Angular, and Vue provide comprehensive solutions that go beyond what the JavaScript Standard Library offers, particularly in building user interfaces and managing state in web applications. These frameworks come with their own sets of conventions and utilities that handle everything from DOM rendering to client-side routing and state management, making them essential tools for complex application development that demands more than just the standard library capabilities.

JavaScript Standard Library Best Practices:

When developing with JavaScript, adhering to best practices ensures that the code is efficient, maintainable, and scalable. Utilizing the JavaScript Standard Library effectively is central to achieving these goals. Developers should understand the capabilities and limitations of the library to fully leverage its features while avoiding potential pitfalls.

JavaScript's array methods, such as `map()`, `filter()`, `reduce()`, and `forEach()`, provide powerful tools for data manipulation. Best practices involve using these methods to write concise, declarative code that is easy to read and debug. For instance, `map()` can be used for transforming data, while `reduce()` is excellent for deriving a single value from an array.

The string functions in JavaScript, such as `includes()`, `startsWith()`, `endsWith()`, and `replace()`, are crucial for text processing. Developers should use these functions to handle and manipulate strings effectively, ensuring operations like searching within a string or replacing content are performed efficiently.

JavaScript provides numerous methods for objects, such as `Object.keys()`, `Object.values()`, and `Object.entries()`. These methods should be used to facilitate object manipulation, making it easier to iterate over properties or convert objects into arrays for further processing.

Handling dates correctly is a common challenge in JavaScript. Utilizing `Date` objects and methods like `Date.parse()` and `Date.UTC()` is recommended for managing dates and times accurately. Developers should also be aware of time zone implications when manipulating date objects.

JSON (JavaScript Object Notation) methods, `JSON.parse()` and `JSON.stringify()`, are indispensable for data interchange between clients and servers. Best practices include using these methods to serialize and deserialize complex data structures efficiently.

The use of `try-catch` blocks is a best practice for error handling in JavaScript. This approach allows developers to gracefully handle errors that may occur during runtime, especially when dealing with external resources or parsing data.

While JavaScript's regular expressions are powerful for pattern matching, they should be used judiciously. Best practices recommend using simple string methods when possible and reserving regular expressions for more complex text processing tasks to ensure code clarity and performance.

Developers must be mindful of memory usage, especially in large-scale applications. Avoiding memory leaks by properly managing closures, listeners, and large data structures is crucial. Regularly reviewing and refactoring code can help mitigate memory issues.

With the advent of ECMAScript 2015 (ES6) and subsequent versions, using modern syntax such as let, const, arrow functions, and template literals is considered best practice. These features make the code more readable and concise, and they introduce benefits like block-scoping and more predictable function scoping.

Developing modular code using ES6 Modules is a best practice in modern JavaScript development. It promotes better organization of the codebase, makes it testable, and enhances code reuse. Utilizing `import` and `export` statements can significantly improve code manageability and scalability.

Asynchronous programming is critical in JavaScript, particularly for handling IO-bound operations. Using Promises and `async/await` for asynchronous code is a best practice, as it leads to cleaner, more readable code and better handling of asynchronous operations.

While polyfills allow developers to use modern features in older environments, their use should be judicious. Best practices involve loading polyfills only when necessary and ensuring they do not override native implementations in environments that support them.

Testing is essential to ensure the quality and reliability of JavaScript code. Using testing frameworks and rigorously testing components can help catch bugs early and maintain high code quality throughout the development process.

The JavaScript landscape is continually evolving, with new features and best practices emerging regularly. Developers are encouraged to stay informed about the latest developments in ECMAScript and the JavaScript Standard Library to keep their skills relevant and their codebases modern and efficient.

JavaScript Standard Library Anti-Patterns:

Summarize this topic in 7 paragraphs. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

When working with the JavaScript Standard Library, developers can occasionally fall into certain traps known as anti-patterns. These anti-patterns represent inefficient, error-prone, or problematic uses of the library that can lead to buggy code, performance issues, or maintenance headaches. Recognizing and avoiding these pitfalls is essential for writing clean, effective JavaScript.

A common anti-pattern in JavaScript involves improper use of array methods such as `map()`, `filter()`, and `reduce()`. For instance, using `map()` solely for the side effects of iterating over an array, instead of its intended purpose to create a new transformed array, can lead to confusing and inefficient code. Similarly, chaining these methods without considering their performance implications can result in unnecessary computations and slow execution times.

The `delete` operator in JavaScript is used to remove properties from objects. However, overusing `delete` can lead to performance degradation, especially in high-performance environments. This is because `delete` modifies the shape of the underlying object, potentially leading to slower property access and optimization issues within JavaScript engines.

Another anti-pattern is ignoring or misusing JavaScript's prototypal inheritance model. For example, directly adding or overriding methods on an object's prototype without understanding the consequences can lead to unexpected behavior, especially when the objects are widely used across the codebase. This practice can also cause issues with library updates and compatibility.

Excessive reliance on global variables is a widespread anti-pattern in JavaScript. Globals can lead to code that is hard to manage and debug due to conflicts in variable names and values that are overwritten unknowingly. Best practice involves minimizing the use of global scope and instead using modules or closures to encapsulate variables.

Poor error handling, such as ignoring errors or relying solely on `console.log()` for debugging, is a significant anti-pattern. Effective error management typically involves using try-catch blocks and proper error propagation with `throw`, which ensures that functions fail safely and predictably when encountering exceptional conditions.

Lastly, neglecting to use modern JavaScript syntax and features introduced in ECMAScript 2015 and later versions is an anti-pattern that can keep code from being concise and performant. Features like arrow functions, template literals, destructuring, and let/const for variable declarations provide improvements in scope management, readability, and functionality that older approaches lack.

JavaScript Standard Library Security

Security is a crucial aspect when using the JavaScript Standard Library, as vulnerabilities within the library can lead to potential exploits in web applications. Developers must ensure that their use of JavaScript functions and objects does not open up security holes, especially when handling user input or performing operations on sensitive data. Awareness and adherence to security best practices can mitigate risks associated with client-side scripting.

One of the fundamental security practices in JavaScript involves the safe handling of data types and structures provided by the JavaScript Standard Library. This includes using methods like `parseInt()` with a radix parameter to avoid errors in number parsing and employing `Array` methods that prevent mutations which could lead to unexpected behaviors. Proper management of data structures helps prevent vulnerabilities such as code injection and data leakage.

The `eval()` function and similar constructor functions like `new Function()` pose significant security risks when used carelessly. These functions can execute arbitrary code which can be exploited to inject malicious code into applications. Avoiding their use, or applying stringent validations before their use, is a critical security practice in modern web development.

Modifying objects' prototypes at runtime, a feature supported by the JavaScript Standard Library, can lead to prototype pollution. This vulnerability can allow attackers to modify an object's prototype, potentially altering the behavior of an application in malicious ways. Developers should avoid directly modifying prototypes of standard built-in objects and employ libraries or frameworks that safely manage prototype changes.

Robust error handling is vital for maintaining security in JavaScript applications. This involves not only catching errors but also ensuring that error messages do not expose sensitive information to the users or potential attackers. Using try-catch blocks and handling specific error types can help secure applications against unexpected failures that could be used as vectors for attacks.

While `JSON.parse()` and `JSON.stringify()` are secure for handling JSON data, ensuring that the data being parsed or transformed does not contain sensitive information is crucial. Care must be taken to validate and sanitize incoming data before parsing and to avoid exposing data through JSON that can be exploited in cross-site scripting (XSS) attacks.

Global objects and variables can be a source of security vulnerabilities in JavaScript. They can be accessed or modified by any script running in the same global context, which can lead to data corruption or unauthorized access. Best practices recommend minimizing the use of global variables and constants, encapsulating functionalities within modules or IIFEs (Immediately Invoked Function Expressions) to limit scope and exposure.

Finally, keeping all JavaScript libraries and dependencies updated is essential for security. This includes the JavaScript Standard Library functionalities extended or used by third-party libraries. Developers should regularly check for updates and security patches to ensure that vulnerabilities are addressed promptly, thereby protecting applications from known exploits and attacks.

JavaScript Standard Library and Unit Testing:

Unit testing in JavaScript involves testing individual components or functions of a web application to ensure they work as expected. The JavaScript Standard Library itself does not directly support unit testing; instead, developers use various testing frameworks and libraries designed to integrate seamlessly with JavaScript environments. These tools provide the necessary functionality to create and run tests, simulate user interactions, and check the output against expected results, thereby supporting the development of reliable and bug-free code.

Several popular testing frameworks are used in the JavaScript community, such as Jest, Mocha, and Jasmine. These frameworks offer a rich set of features that make it easier to write comprehensive tests. For example, Jest is widely favored for its zero-configuration setup and built-in assertion library. Below is an example of a simple unit test using Jest to test a function that adds two numbers:

```javascript // sum.js function sum(a, b) {

   return a + b;

// sum.test.js const sum = require('./sum'); test('adds 1 + 2 to equal 3', () ⇒ {

   expect(sum(1, 2)).toBe(3);

This code demonstrates a basic unit test where the `sum` function is tested to ensure it correctly adds two numbers.

JavaScript testing frameworks integrate well with build tools like Webpack and continuous integration (CI) systems such as Jenkins, Travis CI, and GitHub Actions. This integration allows automated running of tests whenever changes are made to the codebase, ensuring that new code does not break existing functionality. For instance, a Jenkins pipeline can be configured to run Jest tests with each build, providing immediate feedback on the impact of changes.

```shell pipeline {

   agent any
   stages {
       stage('Test') {
           steps {
               sh 'npm test'
           }
       }
   }

This Jenkins pipeline configuration automatically runs tests defined in the `npm test` script, which is typically configured to run a JavaScript testing framework like Jest.

While unit testing is crucial, it presents challenges such as ensuring adequate test coverage and managing tests for asynchronous code. Best practices include writing tests that cover a significant portion of the codebase, including edge cases, and using mocking libraries like Sinon to handle external dependencies and asynchronous behaviors. Properly structuring tests to reflect the application architecture and maintaining clean, readable test code are also essential for effective testing.

```javascript // asyncFunction.test.js const fetchData = require('./fetchData'); jest.mock('./fetchData');

test('fetches data successfully from an API', async () ⇒ {

   const mockData = { data: '12345' };
   fetchData.mockResolvedValue(mockData);
   await expect(fetchData('url')).resolves.toEqual(mockData);

This example shows how to test asynchronous functions using Jest's mocking capabilities to simulate API calls, ensuring the function handles responses correctly.

JavaScript Standard Library and Performance:

Performance optimization is critical when developing applications using the JavaScript Standard Library, as efficient use of its features can significantly impact the application's speed and responsiveness. JavaScript's performance is closely tied to how well developers leverage built-in methods and objects. For example, using `Array.prototype.map()` and `Array.prototype.filter()` efficiently can avoid unnecessary computations and reduce execution time. Developers need to be aware of the cost associated with deep object manipulations and heavy use of immutable data structures which can lead to increased memory usage and slower processing times.

To maximize performance, it's essential to use the most appropriate methods for data handling. For instance, while both `Array.prototype.forEach()` and `for` loops can iterate over arrays, the traditional `for` loop often outperforms `forEach()` in high-performance scenarios due to fewer function call overheads:

```javascript let sum = 0; const numbers = [1, 2, 3, 4, 5];

// Using forEach numbers.forEach(num ⇒ {

   sum += num;

// Using for loop for (let i = 0; i < numbers.length; i++) {

   sum += numbers[i];

In this example, using a `for` loop may be more performant, especially for large arrays, because it avoids the additional overhead of function calls involved in `forEach()`.

Effective management of memory and resources is another key aspect of optimizing performance with the JavaScript Standard Library. Avoiding memory leaks by properly managing closures and references, especially in large and complex applications, is crucial. Moreover, developers should use tools like the Chrome DevTools for profiling and tracking memory usage to identify and rectify performance bottlenecks:

```javascript function createLargeData() {

   const largeData = new Array(1000000).fill('data');
   return function () {
       return largeData;
   }

const getData = createLargeData(); console.log(getData()); ```

This code demonstrates creating a large dataset that, if not managed carefully, could lead to significant memory usage over time, particularly if such functions are called repeatedly without releasing unused data.

The modern ECMAScript standards have introduced features that can help improve performance when used correctly. Features like Typed Arrays for handling binary data, and efficient methods like `Array.prototype.includes()` for checking presence, offer more optimized solutions than their traditional counterparts. Using these advanced features judiciously can lead to cleaner code and better performance:

```javascript // Using Typed Array for handling large volume of numerical data efficiently const buffer = new ArrayBuffer(1024); const int32View = new Int32Array(buffer);

for (let i = 0; i < int32View.length; i++) {

   int32View[i] = i * 2;

This example shows how Typed Arrays can be used for efficiently processing and manipulating a large volume of binary data, which is ideal for applications involving audio and video processing, or any scenario where performance is critical.

JavaScript Standard Library and WebAssembly:

WebAssembly (commonly abbreviated as Wasm) is a binary instruction format for a stack-based virtual machine, designed to enable high-performance applications on web pages. It is supported in modern web browsers through the JavaScript API, allowing Wasm modules to be loaded and executed alongside JavaScript. This integration facilitates seamless interaction between Wasm and the JavaScript Standard Library, where JavaScript functions can invoke Wasm-compiled code, and vice versa. Wasm is designed to work alongside JavaScript, complementing rather than replacing it, by allowing developers to run performance-critical code at near-native speed.

To use WebAssembly in a web environment, developers typically load Wasm modules using the JavaScript fetch API, followed by instantiation with WebAssembly.instantiate(). This process involves fetching the Wasm binary, compiling it, and instantiating it, all within the JavaScript context. The following code snippet demonstrates how to load a Wasm module and call its exported functions:

```javascript fetch('module.wasm').then(response ⇒

 response.arrayBuffer()

 WebAssembly.instantiate(bytes)

 console.log("Called from Wasm: ", results.instance.exports.exportedFunction());

This example fetches a Wasm module, compiles and instantiates it, and finally calls an exported function named `exportedFunction`.

The integration between JavaScript and WebAssembly goes beyond simple function calls. JavaScript can pass data to Wasm modules, and Wasm can return data back to JavaScript. This is typically done through shared ArrayBuffers, which are used to create views like Uint8Array or Float32Array that both JavaScript and Wasm can read and write. Additionally, JavaScript can import its functions into Wasm, allowing the Wasm code to call back into the JavaScript context. This two-way communication enables complex interactions and enhances the capabilities of web applications by combining JavaScript's flexibility with Wasm's performance.

```javascript const importObject = {

 imports: {
   importedFunc: arg => console.log(arg)
 }

WebAssembly.instantiateStreaming(fetch('module.wasm'), importObject)

 .then(obj => obj.instance.exports.exportedFunc());

This code sets up an import object that includes a JavaScript function (`importedFunc`), which is then accessible within the Wasm module.

The use of WebAssembly extends the capabilities of web applications, enabling them to perform tasks that were previously challenging or inefficient in JavaScript alone. Typical use cases include applications requiring complex numerical calculations, graphics rendering, and games, where performance is critical. By compiling code from languages like C, C++, or Rust into Wasm, developers can achieve performance close to native execution speeds, while still leveraging the JavaScript Standard Library for UI interactions, network requests, and other browser-specific functionalities. This combination offers a powerful toolset for developing advanced, high-performance web applications.

JavaScript Standard Library Automation with Python

Summarize this topic in 3 paragraphs. Give 3 code examples. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

JavaScript Standard Library Automation with Java

Summarize this topic in 3 paragraphs. Give 3 code examples. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

JavaScript Standard Library Automation with JavaScript

Summarize this topic in 3 paragraphs. Give 3 code examples. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

JavaScript Standard Library Automation with Golang

Summarize this topic in 3 paragraphs. Give 3 code examples. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

JavaScript Standard Library Automation with Rust

Summarize this topic in 3 paragraphs. Give 3 code examples. Make the Wikipedia or other references URLs as raw URLs. Put a section heading for each paragraph. Section headings must start and end with 2 equals signs. Do not put double square brackets around words in section headings. You MUST put double square brackets around ALL computer buzzwords, product names, or jargon or technical words.

JavaScript Standard Library Glossary:

Array: An object in JavaScript that is used to store multiple values in a single variable. It provides methods like `push`, `pop`, `map`, and `filter` to perform operations on lists of items.

Function: In JavaScript, a function is a block of code designed to perform a particular task. It is executed when “something” invokes it (calls it).

Object: A collection of properties, where a property is an association between a key (or name) and a value. In JavaScript, nearly all objects are instances of Object.

Prototype: An object from which other objects inherit properties and methods. Prototype-based inheritance is a feature in JavaScript that allows object properties and methods to be shared.

Scope: Defines the visibility of variables and functions in areas of the code. JavaScript uses lexical scoping, where the scope of a variable is defined by its location within the source code.

Closure: A feature in JavaScript where an inner function has access to the outer (enclosing) function's variables—scope chain, even after the outer function has returned.

Promise: An object that represents the eventual completion (or failure) and the resulting value of an asynchronous operation. It allows you to associate handlers with an asynchronous action's eventual success value or failure reason.

JSON (JavaScript Object Notation): A lightweight data-interchange format that is easy for humans to read and write and easy for machines to parse and generate. JSON is often used to transmit data between a server and web application.

Event Loop: A programming construct that waits for and dispatches events or messages in a program. It works by making requests to perform some operation in a loop while waiting for a response.

Callback Function: A function passed into another function as an argument, which is then invoked inside the outer function to complete some kind of routine or action. This is a common feature for handling asynchronous operations in JavaScript.

Garbage Collection: An automatic memory management feature that periodically searches for and frees up memory that is no longer in use by the program, helping to prevent memory leaks and optimize performance in JavaScript applications.

Hoisting: A JavaScript mechanism where variable and function declarations are moved to the top of their containing scope before code execution begins, regardless of where they are defined in the source code.

Immutable: A type of variable whose value cannot be changed once it has been set. In JavaScript, strings and numbers are immutable by default, meaning that any changes to them actually create new values.

Lexical Environment: The environment in which a piece of code is executed in JavaScript, which includes any local variables that are in-scope. Lexical environments also contain a reference to the outer (enclosing) environment, essential for creating closures.

This Keyword: A keyword in JavaScript that refers to the object it belongs to, having different values depending on where it is used: in a method, alone, in a function, or in a function in strict mode.

Execution Context: The environment in which JavaScript code is evaluated and executed. Each execution context has its own variables object, scope chain, and the value of “this”, and may represent the evaluation of a function or any block of code.

Spread Operator: An operator in JavaScript that allows an iterable such as an array or string to be expanded in places where zero or more arguments (for function calls) or elements (for array literals) are expected.

Destructuring Assignment: A JavaScript expression that makes it possible to unpack values from arrays, or properties from objects, into distinct variables. This feature enhances the ease of working with data structures.

Template Literals: Special types of string literals in JavaScript that allow embedded expressions, which can include multi-line strings and string interpolation features with `${expression}` syntax.

ECMAScript Modules (ESM): A module system in modern JavaScript that enables a standardized method of organizing and importing/exporting values in and between files, using `import` and `export` statements.

Arrow Functions: A concise syntax for writing function expressions in JavaScript that does not bind its own `this`, `arguments`, `super`, or `new.target`. These functions are best suited for non-method functions and they can not be used as constructors.

Class: A syntactic sugar in JavaScript that provides a much simpler and clearer syntax to create objects and deal with inheritance. Despite the syntax, JavaScript classes are still based on prototypal inheritance.

Set: An object that lets you store unique values of any type, whether primitive values or object references. Set supports operations like addition, removal, and traversal, which make it useful for data handling where uniqueness is required.

Map: A collection of keyed data items, just like an Object. But unlike an object, a Map's keys can be of any type and maintains the insertion order of the keys.

Async/Await: Special syntax to work with promises in a more comfortable fashion. `async` makes a function return a Promise automatically, and `await` is used to pause the function execution until the Promise resolves, making the asynchronous code easier to read and write.

Generator Function: A function that can stop midway and then continue from where it stopped. Upon each call to the generator's `next()` method, the generator resumes execution until it reaches the next `yield` statement.

Event Propagation: The way in which an event travels through the DOM's tree structure, allowing for the defining of the order of how event handlers are called. Event propagation can be managed with methods like `stopPropagation()` or `preventDefault()`.

Fetch API: A modern interface in JavaScript that allows HTTP requests to be made to web servers. It returns promises and is a more powerful and flexible feature than older methods like XMLHttpRequest.

WeakMap: A collection of key/value pairs in which the keys are weakly referenced. The keys of a WeakMap are objects and the values can be arbitrary values. If there is no other reference to the key stored in the WeakMap, they can be garbage collected.

Service Worker: A script that your browser runs in the background, separate from a web page, opening the door to features that don't need a web page or user interaction. Service Workers are used mainly for features like push notifications and background sync.

Module Namespace Object: An object in JavaScript that encapsulates all the exports of an ECMAScript Module (ESM) as properties of this object. It is created when a module is imported using the `import * as name from “module”` syntax, allowing access to all of a module's exports via a single variable.

BigInt: A built-in object in JavaScript that provides a way to represent whole numbers larger than 2^53 - 1, which is the largest number the Number type can safely represent. BigInt is useful for handling large integers without losing precision.

Symbol: A primitive data type and unique token that can be used as an identifier for object properties. Each Symbol value returned from `Symbol()` is unique, allowing properties of objects to be keyed by a value that won't collide with any other properties, even if they have the same name.

Proxy: An object in JavaScript that wraps another object and intercepts operations, like reading/writing properties and method invocation, which is useful for logging, profiling, and interface checking, among other things.

Reflect: An object that provides methods for interceptable JavaScript operations analogous to those performed by the Proxy handlers. It is used for forwarding default operations from the handler to the target.

ArrayBuffer: A generic fixed-length container for binary data. They are used to represent a generic, fixed-length raw binary data buffer, which can then be accessed with an array-like view.

DataView: A low-level interface that provides a protocol for reading and writing multiple number types in an ArrayBuffer irrespective of the platform's endianness.

Typed Arrays: Objects that provide a mechanism for accessing raw binary data much like an array of integers or floating-point numbers. They are much more efficient for handling large quantities of data than the conventional JavaScript arrays.

RequestAnimationFrame: A method that tells the browser to perform animations and repaints, and it calls a specified function to update an animation before the next repaint. The method takes a callback as an argument to be invoked before the repaint.

DOM (Document Object Model): A programming interface for web documents. It represents the page so that programs can change the document structure, style, and content. The DOM represents the document as nodes and objects; that way, programming languages can interact with the page.

EventListener: A procedure in JavaScript that waits for an event to occur, like a user clicking a button, and then executes a specific function in response. Event listeners are fundamental to handling user interactions within web pages.

Local Storage: A web storage object that allows JavaScript sites and apps to store and access data right in the browser with no expiration date. This data persists even after the browser window is closed, making it different from Session Storage.

Session Storage: Similar to Local Storage, but it is designed to store data for one session and is cleared when the browser tab is closed. It provides a way to retain information across page reloads at a session level.

CORS (Cross-Origin Resource Sharing): A JavaScript security feature that allows or restricts requested resources on a web server depending on where the HTTP request was initiated. This policy is used to secure web apps by preventing malicious data breaches.

AJAX (Asynchronous JavaScript and XML): A set of web development techniques using many web technologies on the client-side to create asynchronous web applications. With AJAX, web applications can send and retrieve data from a server asynchronously without interfering with the display and behavior of the existing page.

JSONP (JSON with Padding): A method used in JavaScript to request data from a server residing in a different domain than the client. JSONP makes use of script tags for adding extra data in the query string, requesting resources, and receiving responses wrapped in a function.

Canvas API: An HTML element used with JavaScript that allows for dynamic, scriptable rendering of 2D shapes and bitmap images. It is a low-level, procedural model that updates a bitmap and does not have a built-in scene graph.

WebSockets: An advanced technology that makes it possible to open an interactive communication session between the user's browser and a server. With WebSockets, you can send messages to a server and receive event-driven responses without having to poll the server for a reply.

Shadow DOM: A method of combining multiple DOM trees into one hierarchy and keeping some of the DOM tree hidden and separate from the main document DOM tree. It is used in web components to encapsulate styles and markup.

MutationObserver: An interface that allows JavaScript to observe changes to the DOM, including attribute modifications, node additions, and deletions. It is designed as a replacement for the older DOM event-based mutation events, providing a more robust and performant solution to DOM modifications.

Research:

• JavaScript Standard Library on DuckDuckGo
• JavaScript Standard Library on Google.com
• JavaScript Standard Library on O'Reilly
• JavaScript Standard Library on GitHub

• JavaScript Standard Library on javatpoint.com
• JavaScript Standard Library on w3schools.com
• JavaScript Standard Library on tutorialspoint.com
• JavaScript Standard Library on FreeCodeCamp.org

• JavaScript Standard Library on AWS Docs
• JavaScript Standard Library on Kubernetes.io
• JavaScript Standard Library on docs.microsoft.com
• JavaScript Standard Library on GCP Docs
• JavaScript Standard Library on IBM Docs
• JavaScript Standard Library on Red Hat Docs
• JavaScript Standard Library on Oracle Docs

• JavaScript Standard Library on YouTube
• JavaScript Standard Library on Reddit
• JavaScript Standard Library on scholar.google.com
• JavaScript Standard Library on Stackoverflow
• JavaScript Standard Library on Quora
• JavaScript Standard Library on Dzone
• JavaScript Standard Library on Hacker Noon
• JavaScript Standard Library on InfoQ.com

Fair Use Sources:

• JavaScript Standard Library for Archive Access for Fair Use Preservation, quoting, paraphrasing, excerpting and/or commenting upon

navbar_JavaScript Standard Library

JavaScript Standard Library: JavaScript Standard Library Glossary, JavaScript Standard Library Alternatives, JavaScript Standard Library Best Practices, JavaScript Standard Library Anti-Patterns, JavaScript Standard Library Security, JavaScript Standard Library and Programming Languages, JavaScript Standard Library Automation with JavaScript, Python and JavaScript Standard Library, Java and JavaScript Standard Library, JavaScript and JavaScript Standard Library, TypeScript and JavaScript Standard Library, JavaScript Standard Library Alternatives, JavaScript Standard Library Bibliography, JavaScript Standard Library DevOps - JavaScript Standard Library SRE - JavaScript Standard Library CI/CD, Cloud Native JavaScript Standard Library - JavaScript Standard Library Microservices - Serverless JavaScript Standard Library, JavaScript Standard Library Security - JavaScript Standard Library DevSecOps, Functional JavaScript Standard Library, JavaScript Standard Library Concurrency, Async JavaScript Standard Library, JavaScript Standard Library and Data Science - JavaScript Standard Library and Databases, JavaScript Standard Library and Machine Learning, JavaScript Standard Library Courses, Awesome JavaScript Standard Library, JavaScript Standard Library GitHub, JavaScript Standard Library Topics

Most Common topics:

. (navbar_JavaScript Standard Library – see also navbar_full_stack, navbar_javascript, navbar_node, navbar_software_architecture)

Create a list of the top 30 JavaScript Standard Library topics with no description or definitions. Sort by most common. Include NO description or definitions. Put double square brackets around each topic. Don't number them, separate each topic with only a comma and 1 space.