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It is best known as a JavaScript standard intended to ensure the interoperability of web pages across different web browsers. [2] It is standardized by Ecma International in the document ECMA-262 . ECMAScript is commonly used for client-side scripting on the World Wide Web , and it is increasingly being used for server-side applications and ...
The key to understanding design patterns such as IIFE is to realize that prior to ES6, JavaScript only featured function scope (thus lacking block scope), passing values by reference inside closures. [9] This is no longer the case, as the ES6 version of JavaScript implements block scoping using the new let and const keywords. [10]
The 6th edition, ECMAScript 6 (ES6) and later renamed to ECMAScript 2015, was finalized in June 2015. [ 4 ] [ 30 ] This update adds significant new syntax for writing complex applications, including class declarations ( class Foo { ...
Babel is a free and open-source JavaScript transcompiler that is mainly used to convert ECMAScript 2015+ (ES6+) code into backwards-compatible JavaScript code that can be run by older JavaScript engines. It allows web developers to take advantage of the newest features of the language. [4]
A snippet of JavaScript code with keywords highlighted in different colors. The syntax of JavaScript is the set of rules that define a correctly structured JavaScript program. The examples below make use of the log function of the console object present in most browsers for standard text output.
CommonJS's specification of how modules should work is widely used today for server-side JavaScript with Node.js. [1] It is also used for browser-side JavaScript, but that code must be packaged with a transpiler since browsers don't support CommonJS. [1]
Though most polyfills target out-of-date browsers, some exist to simply push modern browsers forward a little bit more. Lea Verou's -prefix-free polyfill is such a polyfill, allowing current browsers to recognise the unprefixed versions of several CSS3 properties instead of requiring the developer to write out all the vendor prefixes.
A JavaScript engine is a software component that executes JavaScript code. The first JavaScript engines were mere interpreters, but all relevant modern engines use just-in-time compilation for improved performance. [53] JavaScript engines are typically developed by web browser vendors, and every major browser has one.