Introduction to JavaScript

What is JavaScript?

JavaScript (often abbreviated as JS) is a high-level, interpreted, lightweight programming language that is most commonly used to add interactivity, dynamic behavior, and functionality to websites.

It is one of the core technologies of the web, alongside HTML and CSS. While HTML gives structure and CSS handles presentation, JavaScript brings websites to life — enabling features like animations, form validations, sliders, dynamic content updates, and more.

Key features of JavaScript:

• Runs in the browser (client-side), but can also run on servers (with platforms like Node.js)
• Supports object-oriented, functional, and event-driven programming
• Dynamically typed and loosely structured
• Powered by a massive ecosystem of libraries and frameworks (React, Angular, Vue, etc.)

A Brief History of JavaScript

• 1995: JavaScript was created by Brendan Eich at Netscape in just 10 days. It was originally called Mocha, then LiveScript, and finally became JavaScript
• Why the name JavaScript? It was a marketing move — Java was very popular at the time, and Netscape wanted to ride the hype wave. Despite the name, JavaScript and Java are completely different languages.
• 1996: Microsoft entered the scene with its own version called JScript.
• 1997: JavaScript was standardized under the name ECMAScript (ES) by ECMA International. This ensured consistency across browsers.
• 2009: Node.js was released, allowing JavaScript to run on servers, opening the door to full-stack development.
• 2015: A major update, ES6 (ECMAScript 2015), introduced modern features like let, const, arrow functions, classes, and modules — a turning point in the language's evolution.
• Today: JavaScript is everywhere — from web and mobile apps to server-side code, desktop applications, games, IoT devices, and more.