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01. JavaScript Introduction

JS kya hai, browser me kaise chalta hai, aur pehla program.

Is chapter me cover hoga:

1. JavaScript kya hai? (Zero se)

Soch lo website ek robot hai.

• HTML = robot ka body (haath, pair, structure)
• CSS = rang-roop (paint, clothes)
• JavaScript = dimaag + buttons dabane par reaction

Jab aap kisi button pe click karte ho aur kuch change hota hai — wahi JS ka kaam hai.

Full form: JavaScript (log short me JS kehte hain).
Ye programming language hai — isme conditions, loops, functions sab hote hain.

2. Browser me JS kaise chalti hai?

Aapke phone/laptop ka browser (Chrome, Firefox…) ke andar ek JS engine hota hai.

1. HTML page load hoti hai
2. Agar page me <script> tag hai, engine us code ko padhta hai
3. Code chalata hai — text badal sakta hai, alert dikha sakta hai, calculation kar sakta hai

Aapko abhi koi software install karne ki zaroorat nahi. Browser hi kaafi hai.

3. console.log — aapka pehla dost

console.log(...) screen pe badi baat nahi likhta. Ye Developer Console me message bhejta hai — jaise notebook me note.

Seekhne ke time ye sabse useful cheez hai: “kya value aa rahi hai?” check karne ke liye.

Practice 1 — console.log

Neeche code me console.log hai. Run Code dabao, phir output box me message dekho.

Practice 2 — alert

alert browser me popup dikhata hai. Run karke dekho.