JavaScript Kaise Kaam Karta Hai? | JavaScript Ki Working Samjhein

JavaScript web development mein ek bahut important programming language hai. Agar aapne kabhi socha hai ki JavaScript kaise work karta hai, toh yeh video aapke liye hai!

JavaScript ek client-side scripting language hai jo browser mein directly run hoti hai. Matlab, jab aap website pe visit karte hain, toh jo interactive elements aap dekhte hain, jaise buttons, forms, animations, unko handle karne ka kaam JavaScript ka hota hai. JavaScript ka main kaam user interactions ko handle karna, dynamic content dikhana, aur webpages ko interactive banana hai.

• 1. JavaScript Engine:

  JavaScript ko execute karne ke liye har browser mein ek engine hota hai. Jaise Chrome ka engine V8 hai, aur Firefox ka engine SpiderMonkey hai. Yeh engines JavaScript code ko samajhte hain aur usse machine code mein convert karte hain.

• 2. Single-threaded Language:

  JavaScript ek single-threaded language hai, iska matlab hai ki ek time par ek hi operation execute hota hai. JavaScript code ek ek step karke execute hota hai, aur agar koi task complete nahi hota, toh JavaScript usko queue mein rakh leta hai.

• 3. Event Loop:

  JavaScript mein Event Loop ka concept hota hai jo asynchronous code ko handle karta hai. Jab JavaScript ko koi long task ya API call milti hai, toh wo task event loop mein chala jata hai aur baaki code execute hota rehta hai. Jab task complete hota hai, tab wo event loop se execute hota hai.

• 4. Call Stack:

  Call stack JavaScript ke execution flow ko track karta hai. Jab bhi koi function call hota hai, wo call stack mein add ho jata hai. Jab function ka kaam complete hota hai, toh wo stack se remove ho jata hai.

• 5. Web APIs:

  JavaScript browser ke saath interact karne ke liye Web APIs ka use karta hai, jaise DOM (Document Object Model), setTimeout, fetch, aur localStorage. Ye APIs JavaScript ko allow karti hain ki wo browser ke features ko access kar sake.

• 6. Asynchronous Code:

  JavaScript mein aap asynchronous code likh sakte hain, jaise setTimeout, promises ya async/await. Jab aap asynchronous code likhte hain, tab wo task event loop ke through execute hota hai, aur uska execution baad mein hota hai jab baaki ka code complete ho jata hai.

Ek simple example lete hain:

       console.log( Hello );
       setTimeout(() => {
           console.log( Asynchronous Code );
       }, 2000);
       console.log( World );
       
       Output:
       Hello
       World
       Asynchronous Code
     

Yahaan pe setTimeout asynchronous hai, isliye wo 2000 milliseconds ke baad execute hota hai. Jab tak yeh wait kar raha hota hai, tab tak Hello aur World print ho jata hai.

Toh dosto, aaj humne jaana ki JavaScript kaise kaam karta hai . Humne dekha ki yeh kaise event-driven, single-threaded, aur asynchronous kaam karta hai, aur kis tarah se JavaScript apne engine aur event loop ke through operations ko handle karta hai.