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ECMASCRIPT

JavaScript is indubitably one of the most important programming languages today. Not only is it the standard programming language for modern browsers. Its use at the back end (Node.js) is gaining popularity fast. Even mobile apps, desktop applications, and games for various platforms can be coded in JavaScript with the help of software such as Cordova and Unity. It is, in fact, the most tagged technology in StackOverflow   411  , the popular online discussion forum for programmers.

Since its inception in 1997, JavaScript has remained the best-known implementation of ECMAScript (other implementations include JScript and ActionScript). It has undergone many revisions, especially in recent years. Some features have become deprecated. At the same time, new features continue to be added to JavaScript, as it matures and becomes a more sophisticated yet more versatile language.

This guide is kept current with the annual TC39 release cycle, with the latest revision covering language and standard-library additions through ECMAScript 2026 (ES17) — including iterator helpers, the new Set methods, explicit groupBy() aggregation, resizable ArrayBuffers, and more — alongside every earlier edition back to ES5. Refer to Version Features for a chronological, edition-by-edition summary of what was added when.