The Event Loop and Concurrency Model

The event loop is the mechanism that handles asynchronous callbacks in JavaScript. It allows JavaScript to perform non-blocking operations by offloading tasks to the browser or Node.js runtime.

Example

console.log("Start");

setTimeout(() => {
    console.log("Callback");
}, 0);

console.log("End");

// Output:
// Start
// End
// Callback

Explanation: The setTimeout callback is pushed to the event loop, allowing the rest of the code to run first. The callback is executed after the synchronous code, demonstrating how the event loop handles asynchronous operations.

Application: Understanding the event loop is crucial for avoiding pitfalls like race conditions and ensuring proper execution order in asynchronous JavaScript.