Asynchronous JavaScript
What is Asynchronous Programming?
Asynchronous programming allows JavaScript to handle long-running operations without blocking the main thread. JavaScript is single-threaded, so async operations are crucial for performance.
How JavaScript Handles Async Operations
- Call Stack: Tracks function calls
- Web APIs: Browser-provided async APIs (setTimeout, fetch, etc.)
- Callback Queue: Holds callbacks from async operations
- Event Loop: Moves callbacks from queue to call stack
Common Async Patterns
- Callbacks
- Promises
- Async/Await
- Generators
- Observables (RxJS)
Example 1: Callback-based Async
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Example 2: Fetch API with Promises
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⚠️ Important Concepts
Blocking vs Non-Blocking
Blocking: Code that stops execution until completion
Non-blocking: Code that continues execution immediately
Sync vs Async
Synchronous: Line-by-line execution
Asynchronous: Can execute later, non-sequential
Exercise: Fix the Async Issue
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