JavaScript (often abbreviated as JS) is a programming language primarily used in web development to create dynamic and interactive user interfaces. It was created in 1995 by Brendan Eich while he was working at Netscape Communications. Originally named Mocha, then LiveScript, the language was eventually renamed JavaScript in a marketing move to capitalize on the popularity of Sun Microsystems' Java programming language, though the two are distinct and unrelated. According to Mozilla Developer Network, JavaScript is one of the three core technologies of the World Wide Web.

History

In 1995, Netscape decided it needed a simple scripting language to complement Java for its Navigator web browser. Brendan Eich was recruited and created the first version in just ten days. According to an interview with InfoWorld, the language was designed to be accessible to web designers and amateur programmers. Due to the competitive browser market, Microsoft reverse-engineered the JavaScript interpreter to create its own implementation, called JScript, for Internet Explorer 3. The significant differences between implementations led to compatibility issues, prompting the need for a standardized language specification.

Standardization: ECMAScript

To promote standardization, Netscape submitted JavaScript to Ecma International, an organization that develops standards for information and communication systems. This resulted in the creation of the ECMAScript standard in 1997. As detailed by the official standards body Ecma International, JavaScript is the most well-known implementation of the ECMAScript (ECMA-262) specification. The technical committee TC39 is responsible for evolving the language. Since 2015 (with the release of ES6), ECMAScript has adopted a yearly release cycle, introducing new features and syntax to the language on a regular basis.

Core Features

JavaScript is characterized by several key features:

• –High-Level and Dynamic: It abstracts away most low-level machine details and allows variable types to be determined at runtime (dynamic typing).
• –Multi-Paradigm: It supports multiple programming styles, including procedural, object-oriented (using prototype-based inheritance), and functional programming. According to a guide from freeCodeCamp, this flexibility is one of its core strengths.
• –Just-in-Time (JIT) Compilation: Modern JavaScript engines perform JIT compilation, which compiles the code into machine code at runtime, providing significant performance improvements over purely interpreted languages.
• –Single-Threaded with Event Loop: JavaScript executes on a single thread but handles asynchronous operations (like network requests or user input) using an event loop model, which prevents the user interface from freezing during long-running tasks.

Usage

Client-Side Web Development

This is JavaScript's original and most common use case. It is executed in the user's web browser to manipulate the Document Object Model (DOM), which represents the structure of an HTML document. This allows developers to change content, styles (CSS), and handle user events like clicks and keyboard input. Popular client-side libraries and frameworks like React, Angular, and Vue.js are built on JavaScript to simplify the development of complex single-page applications.

Server-Side Development

With the introduction of Node.js in 2009, JavaScript became a viable language for server-side programming. According to the Node.js Foundation, Node.js allows developers to build scalable network applications using JavaScript's event-driven, non-blocking I/O model.

Other Applications

JavaScript's reach has extended beyond the web. It is used for:

• –Mobile Applications: Frameworks like React Native and NativeScript enable the creation of cross-platform mobile apps.
• –Desktop Applications: Platforms such as Electron allow developers to build desktop applications using web technologies.
• –Game Development: Libraries like Phaser and Three.js are used to create browser-based games.