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Return to JavaScript Version History, JavaScript-ECMAScript

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Creating a detailed summary of ECMAScript 5 (ES5) with comparisons, examples, and links in the format requested would result in a very extensive document. However, I will provide a concise overview of the key features introduced in ES5, including relevant examples, comparisons, and official resources. ECMAScript 5, released in 2009, was a significant milestone in the evolution of JavaScript, introducing many features that addressed common pain points and expanded the language's capabilities.

ECMAScript 5 (ES5) introduced a substantial set of new features and improvements aimed at making JavaScript development more robust and capable. It included enhancements for object manipulation, stricter parsing and error handling modes, and new methods for arrays and objects that are now considered fundamental for modern JavaScript development.

• Language Documentation: s://www.ecma-international.org/ecma-262/5.1/
• GitHub Repository: GitHub usage for ECMAScript proposals and documentation became standard in later versions.
• Official Website: s://www.ecma-international.org/
• Wikipedia: s://en.wikipedia.org/wiki/ECMAScript#5th_Edition

Strict Mode is a feature that allows developers to opt into a restricted variant of JavaScript. It eliminates some silent errors, improves performance, and provides more warnings and errors. JavaScript Code Example: ```javascript 'use strict'; var x = 3.14; // This will throw an error if x has not been declared ``` This feature is somewhat unique to JavaScript as it addresses the language's flexibility. Other languages like Python and Java have strict syntax and error checking by default.

ES5 introduced native support for JSON (JavaScript Object Notation), including `JSON.parse()` and `JSON.stringify()` for parsing and stringifying JSON data. JavaScript Code Example: ```javascript var jsonStr = '{“name”: “John”, “age”: 30}'; var jsonObj = JSON.parse(jsonStr); ``` Most modern languages, including Python and Java, have built-in or library-supported mechanisms for JSON parsing and serialization.

A variety of new Array methods were added in ES5, such as `forEach()`, `map()`, `filter()`, `reduce()`, and more, facilitating functional programming styles. JavaScript Code Example: ```javascript var numbers = [1, 4, 9]; var roots = numbers.map(Math.sqrt); ``` Python's list comprehensions and Java's Streams API introduced in Java 8 offer similar capabilities for collection processing.

ES5 allowed for more precise control over object properties through property descriptors, enabling developers to define properties as readonly, non-enumerable, or non-configurable. JavaScript Code Example: ```javascript Object.defineProperty(object, 'property', {

 value: 123,
 writable: false

}); ``` Python uses decorators to achieve similar effects, while Java utilizes access modifiers like `private`, `protected`, and `public`.

The `bind()` method was introduced to set the `this` value for functions, addressing common issues with `this` keyword behavior in callbacks. JavaScript Code Example: ```javascript var module = {

 x: 42,
 getX: function() {
   return this.x;
 }

}; var retrieveX = module.getX.bind(module); console.log(retrieveX()); // 42 ``` Languages like Python and Java have different mechanisms for managing context and closures, such as using `self` or anonymous classes.

`Object.create()` method was introduced to create a new object with the specified prototype object and properties. JavaScript Code Example: ```javascript var person = {

 isHuman: false,
 printIntroduction: function() {
   console.log(`My name is ${this.name}. Am I human? ${this.isHuman}`);
 }

}; var me = Object.create(person); ``` This approach to object creation and inheritance is unique to JavaScript's prototype-based inheritance model.

ES5 clarified the ability to include trailing commas in object literals, easing version control diffs and code additions. JavaScript Code Example: ```javascript var obj = {

 name: "John",
 age: 30,

}; ``` Trailing commas are also accepted in Python dictionaries and lists, and were later allowed in Java for array and list initializers.

`Date.now()` provides the current timestamp, simplifying the process of obtaining the current time. JavaScript Code Example: ```javascript var timestamp = Date.now(); ``` This method offers functionality similar to Python's `datetime.now()` and Java's `System.currentTimeMillis()`.

`Array.isArray()` was introduced to check if a variable is an array, given that `typeof` returns `'object'` for arrays

. JavaScript Code Example: ```javascript var isArray = Array.isArray([1, 2, 3]); // true ``` Python and Java both have their own type-checking mechanisms, such as `instanceof` in Java and `type()` in Python.

ECMAScript 5 significantly enhanced JavaScript's capabilities, introducing features that addressed common development challenges and expanded the language's functionality. By standardizing JSON support, introducing strict mode, and adding new array and object methods, ES5 made JavaScript development more robust and maintainable. These improvements have had a lasting impact on how JavaScript is written today. For more detailed information, refer to the official documentation and resources provided.

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