JavaScript Programming Language

JavaScript is a high-level, interpreted programming language that is one of the core technologies of the World Wide Web, alongside HTML and CSS. Created by Brendan Eich at Netscape Communications Corporation in 1995 in just 10 days (originally named Mocha, then LiveScript, before being renamed JavaScript in a marketing deal with Sun Microsystems), JavaScript has grown from a simple browser scripting language into the most widely used programming language in the world, according to the Stack Overflow Developer Survey. Key features: dynamic typing: variables are not bound to types, allowing flexible code. Values have types (number, string, boolean, object, undefined, null, symbol, bigint), not variables. Prototype-based object orientation: objects inherit from other objects via prototypes, not classes (though ES6 class syntax provides a familiar abstraction over prototypes). First-class functions: functions are values that can be assigned to variables, passed as arguments, and returned from other functions. Closures: inner functions capture variables from their enclosing scope, enabling data privacy, function factories, and module patterns. Event-driven: JavaScript in browsers responds to user events (click, keydown, submit) via event listeners. Asynchronous: Promises (ES6), async/await (ES2017), the event loop, and callback patterns handle asynchronous operations without blocking the main thread. JSON: JavaScript Object Notation is a native data format derived from JavaScript object literal syntax. ECMAScript specification: the language is standardized as ECMAScript (ECMA-262) by TC39, with annual releases. ES6/ES2015 was a major update introducing classes, modules, arrow functions, let/const, template literals, destructuring, Maps/Sets, and Promises. Ecosystem: npm is the largest package registry. Frameworks include React, Vue, Angular, Node.js, Express, Next.js. TypeScript adds static typing. JavaScript. Multiple implementations (V8, SpiderMonkey, JavaScriptCore).