JavaScript

JavaScript

  [[File:|frameless|alt=]]

Paradigm	Multi-paradigm: event-driven, functional, imperative
Family
Designed by
Developer	Netscape, Mozilla Foundation
First appeared
Typing discipline	Dynamic

JavaScript (often abbreviated as JS) is a high-level, interpreted programming language that conforms to the ECMAScript specification. JavaScript has become one of the core technologies of the World Wide Web, alongside HTML and CSS, as it enables interactive web pages and is thus an essential part of web applications. The vast majority of websites use JavaScript, and all major web browsers have a dedicated JavaScript engine to execute it.

History

JavaScript was created in 1995 by Brendan Eich while he was an engineer at Netscape. Originally developed under the name Mocha, the language was later renamed to LiveScript, and finally to JavaScript, coinciding with the release of Netscape Navigator 2.0. Despite the name, JavaScript is almost entirely unrelated to the Java programming language, and the common naming is generally considered a marketing ploy by Netscape to capitalize on Java's popularity at the time.

Features

JavaScript is characterized by its dynamic typing, prototype-based object-orientation, and first-class functions. It is a multi-paradigm language, supporting imperative, event-driven, and functional programming styles.

Syntax and semantics

JavaScript's syntax is influenced by that of C, though it has fewer low-level facilities. JavaScript supports object-oriented programming with object prototypes, instead of classes (as in C++ or Java). However, with the introduction of ES6 (ECMAScript 2015), JavaScript now supports class-based object-oriented programming as well.

Runtime environment

JavaScript typically runs in a client-side environment (e.g., in a web browser), but it can also be used on the server-side, through environments such as Node.js. This dual capability allows for the development of full-fledged applications that are capable of interacting with a web server and a database.

Usage

JavaScript is used in many aspects of web development. It is used to provide dynamic behavior on websites (e.g., interactive forms, pop-ups, animations), to load content asynchronously via AJAX calls, and to build complex user interfaces with frameworks like React, Angular, and Vue.js.

Security

JavaScript can also be a vector for web security issues, particularly through cross-site scripting (XSS) attacks, where malicious scripts are injected into trusted websites. Modern development practices and frameworks strive to mitigate these risks through various techniques, including content security policies and sandboxing.

See also

• ECMAScript
• JSON
• WebAssembly