🚀The Event Loop — Mastering Async Behavior in JS

🤯 Why JavaScript Feels Asynchronous

JavaScript is single-threaded — it runs one task at a time.
But when Hasnide uses things like:

• setTimeout()

• fetch()

• Promises

• async/await

…it feels asynchronous. That magic is made possible by the event loop.

🧠 Key Components

✅ 1. Call Stack

• The main place where JavaScript executes functions.

• LIFO (Last-In, First-Out) stack.

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✅ 2. Web APIs / Browser APIs

Things like setTimeout, DOM events, fetch() are handled by the browser — not the JS engine itself.

✅ 3. Callback Queue / Task Queue

Once the Web API finishes, the callback is placed into the callback queue.

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✅ 4. The Event Loop

This loop constantly checks:

Is the call stack empty?
If yes → push the next callback from the queue into the stack.

This allows JavaScript to remain non-blocking and responsive.

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🔄 Visual Timeline

🧪 Code in Action

🔍 Stack vs Queue vs Microtasks

✅ Summary

✍️ Written By

📫 chaitanyachopde14@gmail.com

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🌟 Inspired By

• Devsync

• MDN – Concurrency Model & Event Loop

• Real-world DevSync training exercises