JavaScript overview

JavaScript is the dynamic, prototype-based, event-driven language that runs natively in web browsers and, via Node.js / Deno / Bun, on the server. It is the only language that executes directly in the browser, making it the universal language of the web frontend. Modern JavaScript (ES2015+) features classes, modules (ESM), async/await, optional chaining, nullish coalescing, destructuring, and generators. The npm/pnpm/Yarn ecosystem hosts millions of packages. JavaScript powers React, Vue, Angular, Svelte, and every other major UI framework. On the server, Express, Fastify, and NestJS are common choices. JSDoc enables type annotations without a compilation step.