JavaScript
The Event Loop Explained – How JavaScript Really Works
Arko
2025-05-12
5 min read
Ever wondered how JavaScript handles multiple tasks at once if it's single-threaded? In this blog, we break down the event loop and show how it lets JavaScript run asynchronous code smoothly without blocking the main thread.
What Is the Event Loop?
JavaScript runs in a single thread, which means it can only do one thing at a time. So how does it manage tasks like API calls, timers, or DOM events without freezing the browser? That's where the event loop comes in. It works with the call stack, Web APIs, and a task queue to manage asynchronous operations smoothly.
When JavaScript encounters async code (like setTimeout or fetch), it sends that work to the browser's Web APIs and continues executing the rest of the code. Once the async task is ready, the event loop checks if the call stack is clear and then pushes the callback back into the stack to be executed. This creates a non-blocking experience and allows your apps to stay responsive.
Understanding the event loop helps you write better asynchronous code and debug issues like race conditions or unexpected delays. It’s the foundation of concepts like promises, async/await, and more in modern JavaScript.
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