JavaScript Introduction

Subject: JavaScript

JavaScript is a high-level, interpreted scripting language used to add interactivity and dynamic behavior to websites. It was initially developed for browsers, but today, it powers everything from client-side scripts to full-stack web applications and even mobile and desktop apps.

What Is JavaScript?

JavaScript is one of the three core technologies of the web:

  • HTML defines the structure of a webpage
  • CSS defines the appearance
  • JavaScript controls behavior and interactivity

It allows developers to build features such as:

  • Dynamic page updates
  • Form validation
  • Modal pop-ups
  • Content sliders
  • API requests
  • Real-time notifications
  • Interactive animations

Brief History of JavaScript

  • 1995: Created by Brendan Eich at Netscape as "Mocha"
  • Renamed to LiveScript, then finally to JavaScript
  • 1997: Became standardized by ECMA International (ECMAScript)
  • Modern JS (ES6+): Introduced major features like arrow functions, classes, modules, and promises

Where Is JavaScript Used?

  • Client-Side (Browser): DOM manipulation, event handling, animations
  • Server-Side: Using platforms like Node.js
  • Mobile Apps: Via frameworks like React Native
  • Desktop Apps: Via Electron
  • Other Areas: Game development, IoT, machine learning, and more

Features of JavaScript

  • Lightweight & Fast
  • Cross-platform (works across all browsers and OS)
  • Object-Oriented & Functional
  • Event-driven Programming
  • Asynchronous Programming with Promises and async/await
  • Huge ecosystem of libraries and frameworks (React, Angular, Vue, etc.)

Example: Simple Alert Box

When the button is clicked, JavaScript runs a function that shows an alert.

JavaScript vs Java – Are They Related?

Despite the name, JavaScript and Java are not the same:

  • Java is a statically typed, compiled language.
  • JavaScript is a dynamically typed, interpreted language.
  • The name "JavaScript" was a marketing move during Java's popularity boom.

Key Takeaways

  • JavaScript is essential for modern, interactive websites
  • Originally built for browsers, now used everywhere (frontend + backend)
  • It follows a multi-paradigm approach (OOP + functional)
  • ECMAScript standard ensures compatibility across browsers
  • Learning JavaScript lays the foundation for React, Node.js, and beyond
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