JavaScript (JS) is a high-level, multi-paradigm programming language primarily used to add interactive elements to websites. Brendan Eich created it in 1995 for Netscape. JavaScript is now a core technology of the web, along with HTML and CSS, and is used by the vast majority of websites. As of June 2025, the current version of JavaScript is ECMAScript 2025 (ES2025).
Key features of JavaScript include dynamic typing, support for event-driven, functional, and imperative programming styles, and asynchronous processing, which allows tasks to run in the background without blocking the main thread. It is also versatile, working in browsers, servers, and mobile apps. JavaScript conforms to the ECMAScript standard, and "JavaScript" is a trademark of Oracle Corporation. JavaScript is free to use and access. Many of its libraries and frameworks, like React and Node.js, are also free.