JavaScript

JavaScript® (often shortened to JS) is a lightweight, interpreted, object-oriented language with first-class functions, most known as the scripting language for Web pages, but used in many non-browser environments as well such as node.js or Apache CouchDB. It is a prototype-based, multi-paradigm scripting language that is dynamic, and supports object-oriented, imperative, and functional programming styles. Read more about JavaScript.

The JavaScript standard is called ECMAScript. As of 2012, all modern browsers fully support ECMAScript 5.1. Older browsers support at least ECMAScript 3. On June 17, 2015, the sixth major version of ECMAScript was published. This version is officially called ECMAScript 2015, but is commonly referred to as ECMAScript 6 or ES6. The documentation we present covers ECMAScript 6 and we've already begun to cover the early bits of ECMAScript 7.

This section of the site is dedicated to the JavaScript language itself, the parts that are not specific to Web pages, or other host environments. For information about APIs specific to Web pages, please see Web APIs and DOM.

JavaScript is not to be confused with the Java programming language. Java is a trademark or registered trademark of Oracle in the U.S. and other countries.

Tutorials

Learn how to program with JavaScript with our guides and tutorials.

Introductory

JavaScript Guide
If you are new to JavaScript, this guide will walk you through the language.
JavaScript technologies overview
Introduction to the web browser JavaScript landscape.
Introduction to Object Oriented JavaScript
Introduction to the concepts of object oriented programming in JavaScript.

Intermediate

A re-introduction to JavaScript
An overview for those who think they know about JavaScript.
JavaScript data structures
Overview of available data structures in JavaScript.
Equality comparisons and sameness
JavaScript provides three different value-comparison operations: strict equality using ===, loose equality using ==, and the Object.is() method.

Advanced

Inheritance and the prototype chain
Explanation of the widely misunderstood and under-estimated prototype-based inheritance.
Strict mode
A restricted variant of JavaScript.
JavaScript typed arrays
JavaScript typed arrays provide a mechanism for accessing raw binary data.
Memory Management
Memory life cycle and garbage collection in JavaScript.
Concurrency model and Event Loop
JavaScript has a concurrency model based on an "event loop".

Reference

Browse the complete JavaScript reference documentation.

Standard objects
Get to know standard built-in objects Array, Boolean, Date, Error, Function, JSON, Math, Number, Object, RegExp, String, Map, Set, WeakMap , WeakSet, and others.
Expressions and operators
Learn more about the behavior of JavaScript's operators instanceof, typeof, new, this, the operator precedence, and more.
Statements and declarations
Learn how do-while, for-in, for-of, try-catch, let, var, const, if-else, switch, and more JavaScript statements and keywords work.
Functions
Learn how to work with JavaScript's functions to develop your applications.

Tools & resources

Helpful tools while writing and debugging your JavaScript code.

Firefox Developer Tools
Scratchpad, Web Console, JavaScript Profiler, Debugger, and more.
Firebug
Edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
JavaScript Shells
A JavaScript shell allows you to quickly test snippets of JavaScript code.
TogetherJS

Collaboration made easy.

Stack Overflow
Stack Overflow questions tagged with "JavaScript".
JavaScript versions and release notes
Browse JavaScript's feature history and implementation status.

Join the JavaScript community

Choose your preferred method for joining the discussion:

Document Tags and Contributors

Last updated by: SphinxKnight,
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