JavaScript (JS) is a dynamic, multi-paradigm programming language and a core technology of the Web, along with HTML and CSS. Created in 1995 by Brendan Eich while at Netscape Communications, JavaScript was initially designed to enhance web pages with interactive elements. Today, it is used by the vast majority of websites—approximately 98.9%—for client-side scripting, making it the dominant language for web interactivity. JavaScript conforms to the ECMAScript standard, with ongoing updates introducing new features and improvements to the language.
JavaScript is known for its flexibility and is used for both client-side and server-side scripting. It is an interpreted language, meaning it runs line-by-line in the browser, although modern browsers use just-in-time compilation for improved performance. Key features include dynamic typing, where variable types can change during runtime, and support for multiple programming styles, including event-driven, functional, and imperative programming. JavaScript engines, such as V8 (Chrome), SpiderMonkey (Firefox), and JavaScriptCore (Safari), are implemented in every major browser to execute JavaScript code. The language also boasts asynchronous capabilities, making it well-suited for modern application development. Recent trends in JavaScript development include the increased use of TypeScript, the rise of meta-frameworks, and the integration of WebAssembly for enhanced performance.