Day 1

JavaScript Introduction

8 min

JavaScript 100 Days

JavaScript ek programming language hai jo websites ko interactive banati hai. Jab aap kisi button par click karte hain, form submit karte hain, ya koi animation dekhte hain — yeh sab JavaScript ka kaam hai.

JavaScript kya hai?

JavaScript (JS) ek lightweight, interpreted programming language hai. Isko 1995 mein Brendan Eich ne sirf 10 din mein banaya tha. Aaj JavaScript duniya ki sabse popular language hai — browser, server (Node.js), mobile apps — har jagah use hoti hai.

Apna pehla JavaScript code

console.log() function se output print karte hain. Yeh developer tools ke Console tab mein dikhta hai.

script.js

javascript

// Apna pehla JavaScript program
console.log("Hello, World!");
console.log("Welcome to CodingSkillUp!");

// Numbers bhi print ho sakte hain
console.log(2025);
console.log(10 + 5); // Output: 15

JavaScript kahan likhte hain?

JavaScript HTML file mein <script> tag ke andar ya alag .js file mein likh sakte hain. Modern development mein hum alag file prefer karte hain.

index.html

html

<!DOCTYPE html>
<html lang="en">
<head>
  <title>My First JS Page</title>
</head>
<body>
  <h1>Hello!</h1>

  <!-- JavaScript — external file -->
  <script src="script.js"></script>
</body>
</html>

Browser Console kholna

F12 ya Ctrl+Shift+I dabao → Console tab kholo. Wahan tumhara output dikhe ga. Yeh har developer ka best friend hai.

🎯 Practice Challenge

Browser console kholo (F12) aur apna naam, age, aur favourite color console.log() se print karo.

Variables — let, const, var