Скачать или смотреть 🚀 FREE LIVE MERN Stack Course | Day 13 | Asynchronous JavaScript (Callbacks, Promises, Async/Await)

🎓 Join my FREE LIVE MERN Stack Course — started from 1st November, streaming every day on YouTube Live!
Welcome to Day 13 of the MERN Stack Live Training Series!
In this session, we dive deep into Asynchronous JavaScript, one of the most important concepts used in real-world web development — especially in React, Node.js, and API-driven applications.
You’ll learn exactly how JavaScript handles async operations using callbacks, promises, and async/await, how the event loop works, and how to avoid callback hell. We also explore real-world scenarios like API calls, timeouts, and handling multiple promises together.

🔍 Topics Covered (Day 13 – Asynchronous JavaScript)

1️⃣ Callbacks – The Beginning of Async JS
What are callbacks?
setTimeout, setInterval examples
Callback pitfalls
What is callback hell?
Why callback hell is bad (pyramid of doom)

2️⃣ Promises – Modern Way to Handle Async Code
Understanding Promise states (pending, fulfilled, rejected)
Creating a promise using new Promise()
resolve and reject
Consuming promises with .then(), .catch(), .finally()
Chaining promises to avoid callback hell

3️⃣ Async / Await – Cleaner & Modern Approach
Why async/await?
Writing synchronous-looking async code
Using await to pause promise execution
Error handling using try...catch
Real API examples (fetch)

4️⃣ Promise Utility Methods (Must Know for Interviews)
Promise.all() → parallel execution
Promise.allSettled() → results of all
Promise.race() → first settled (resolve/reject)
Promise.any() → first fulfilled
Promise.resolve()
Promise.reject()

5️⃣ Understanding the Event Loop
Call stack, Web APIs, Callback queue
How JavaScript executes async code internally
Microtask queue vs macrotask queue
Why promises run faster than setTimeout

6️⃣ Real-World Use Cases

API calls
Timeout + retry logic
Parallel API requests
Loading states in React
Async Node.js operations (file reading, database queries)

💡 Learning Outcome
By the end of this lesson, you’ll understand how JavaScript actually works behind the scenes when handling asynchronous code.
You will learn how to:
✔ Write clean async code using async/await
✔ Avoid callback hell
✔ Manage multiple asynchronous operations
✔ Handle API responses properly
✔ Use Promise utilities to optimize performance
✔ Debug async issues easily
These concepts are essential for React, Node.js, Express, MongoDB, and real-world project development.

💻 What You’ll Learn in the MERN Stack Course:
✅ HTML, CSS, JavaScript (Core + Advanced)
✅ React.js (Frontend)
✅ Node.js & Express.js (Backend)
✅ MongoDB (Database)
✅ API Development + Asynchronous JS
✅ Real Projects + Deployment
✅ Interview Preparation (Frontend + MERN)
✅ AI Tools for Developers
🕗 Time: 9:30 PM – 11 PM (Daily)
📍 Platform: YouTube Live
💬 Join Completely FREE
✨ Be part of this Full-Stack journey — Subscribe now and don’t miss any class!

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