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JavaScript is a single-threaded, synchronous language, but it supports asynchronous programming to handle tasks like API calls, timers, or event listeners without blocking the main thread. Asynchronous tasks can be implemented using callbacks, Promises, or async/await.
Using Callbacks
Callbacks are functions passed as arguments to another function, executed after an asynchronous operation completes. This approach ensures non-blocking execution but can lead to "callback hell" when nested deeply.
Example:
function fetchData(callback) {setTimeout(() => {const data = { name: "Alice", age: 25 };callback(data);}, 2000);}fetchData((data) => {console.log("Data:", data);});Copied!✕CopyOutput after 2 seconds:
Data: { name: 'Alice', age: 25 }Copied!✕CopyUsing Promises
Promises represent the eventual completion or failure of an asynchronous operation. They provide .then() for success and .catch() for error handling, making the code more readable.
Example:
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