JavaScript is a high-level, dynamic programming language that serves as one of the three core technologies of the World Wide Web alongside HTML and CSS. Originally created by Brendan Eich in 1995 for adding interactivity to web pages in Netscape Navigator, JavaScript has evolved into one of the most versatile and widely used programming languages in the world, powering everything from frontend user interfaces to backend servers, mobile apps, and desktop applications.
Modern JavaScript (governed by the ECMAScript specification) supports multiple programming paradigms including object-oriented, functional, and event-driven programming. Key language features include first-class functions, closures, prototypal inheritance, async/await for asynchronous operations, and a rich standard library. The language runs natively in every web browser through built-in JavaScript engines (V8 in Chrome, SpiderMonkey in Firefox) and on servers via Node.js and Deno runtimes.
The JavaScript ecosystem is the largest in software development, with the npm registry hosting over two million packages. Major frameworks and libraries like React, Vue, Angular, Next.js, Express, and NestJS provide structured approaches for building complex applications. TypeScript, a statically typed superset of JavaScript, has become the preferred choice for large-scale projects. JavaScript consistently ranks as the most-used programming language in developer surveys, and its reach across browsers, servers, and mobile platforms is a big part of why.