JavaScript

JavaScript
Name	JavaScript
Paradigm	Multi-paradigm
Designer	Brendan Eich
Developer	Netscape Communications Corporation, ECMA International
Typing	Dynamic, weak, duck
Influenced by	Self, Scheme, Java, C, AWK
Influenced	TypeScript, ActionScript, Dart, CoffeeScript
File ext	.js, .cjs, .mjs

JavaScript. It is a high-level, often just-in-time compiled programming language that conforms to the ECMAScript specification. As a core technology of the World Wide Web, alongside HTML and CSS, it enables interactive web pages and is a foundational part of web applications. The vast majority of websites use it for client-side page behavior, and all major web browsers have a dedicated engine to execute it.

History

JavaScript was created in 1995 by Brendan Eich while working for Netscape Communications Corporation. It was developed in just ten days under the name Mocha, later renamed LiveScript, and finally JavaScript as part of a marketing alliance with Sun Microsystems to promote it alongside Java. To standardize the language, Netscape submitted it to ECMA International, leading to the first edition of the ECMAScript standard in 1997. The early 2000s saw significant development with projects like Ajax, popularized by applications such as Google Maps, which demonstrated its potential for rich web applications. A major turning point was the 2008 release of Google Chrome with its high-performance V8 engine, which spurred rapid performance improvements and the development of the modern ecosystem, including Node.js.

Syntax

The syntax of JavaScript is influenced by C and Java, utilizing curly braces to delimit blocks of code and similar control flow constructs like `if`, `for`, and `while` statements. It is a case-sensitive language and uses the `var`, `let`, and `const` keywords for variable declarations, with significant semantic differences introduced in ECMAScript 2015. Functions are first-class objects, and the language supports object literals and array literals with a concise syntax. Asynchronous operations are commonly handled using promises and the `async`/`await` syntax, which became standard in later ECMAScript editions.

Features

As a multi-paradigm language, it supports event-driven, functional, and imperative programming styles. It features prototype-based object orientation, where objects can inherit properties directly from other objects, rather than from classes. Key features include dynamic typing, where types are associated with values, not variables, and just-in-time compilation performed by engines like V8 and SpiderMonkey. The language also supports higher-order functions, closures, and, since ECMAScript 2015, modules, classes, and iterators, bringing more structure to large-scale application development.

Runtime environments

Originally confined to web browsers like Firefox (using SpiderMonkey) and Microsoft Edge (using Chakra), it now executes in diverse environments. The introduction of Node.js by Ryan Dahl allowed it to run as a server-side technology, enabling the development of scalable network applications. Other significant runtime environments include Deno, created by the same inventor as Node.js, and platforms like React Native and Apache Cordova for building mobile applications. Embedded systems and IoT devices can also run it through engines like JerryScript and Duktape.

Use in web development

On the client side, it manipulates the Document Object Model to dynamically change content, validate forms, control multimedia, and animate images, creating the interactive experience of modern websites like Facebook and YouTube. Single-page applications built with frameworks such as React, Angular, and Vue.js rely heavily on it to manage state and routing without full page reloads. On the server side, platforms like Node.js power the backend of major services including Netflix, LinkedIn, and Uber, handling API requests, database operations, and real-time communication via technologies like WebSocket.

Related technologies

The ecosystem is vast and supported by package managers like npm and Yarn, which host millions of libraries. TypeScript, developed by Microsoft, is a strict syntactical superset that adds static typing and compiles down to it. Transpilers like Babel allow developers to use next-generation syntax from ECMAScript by converting it to older versions for broader browser compatibility. Testing frameworks such as Jest and Mocha are integral to modern development workflows. Its use is also foundational in visualization libraries like D3.js and charting tools for data presentation.

Category:Programming languages Category:Web development