Async await JavaScript

Question

pls expalin me Async await JavaScript

Abhishek Yadav · Answer

async function fetchData() { try { const response = await fetch('https://api.example.com/data'); const data = await response.json(); console.log(data); } catch (error) { console.error('Error fetching data:', error); } } fetchData(); Async await is a feature in JavaScript that allows you to work with asynchronous code in a more synchronous way. When you mark a function with the async keyword, it automatically returns a Promise. Inside an async function, you can use the await keyword to wait for a Promise to resolve before continuing with the code execution. Here's an example of how async await can be used:

Naimish Makwana · Answer

The async and await keywords are special syntax in JavaScript that are used to work with promises in a more comfortable and readable way. Async Function: An async function is a function that implicitly returns a promise. The async keyword before a function means that the function will always return a promise. Any value returned by the function is wrapped in a resolved promise automatically. Here’s an example: async function f() { return 1; } f().then(alert); // 1 In the above example, the function f() returns a resolved promise with the result of 1 . Await Keyword: The await keyword is used inside an async function to pause its execution and wait for a promise to resolve or reject before continuing. Here’s an example: async function f() { let promise = new Promise((resolve, reject) => { setTimeout(() => resolve("done!"), 1000) }); let result = await promise; // wait until the promise resolves alert(result); // "done!" } f(); In the above example, the function execution pauses at let result = await promise; and resumes when the promise settles, with result becoming its result. So, the code shows “done!” after one second12. Remember, the await keyword can only be used inside an async function3. If we try to use await in a non-async function, there would be a syntax error1. This async/await syntax provides a way of maintaining cleaner and more readable code when working with asynchronous operations12. Thanks

Tuhin Paul · Answer

The await keyword can only be used inside an async function. It pauses the execution of the async function until the awaited Promise settles (either resolves or rejects). The await keyword then returns the resolved value of the Promise. // Asynchronous function declared with async keyword async function asyncFunction() { // Create a Promise that resolves after 2 seconds const delayPromise = new Promise(resolve => { setTimeout(() => { resolve('Resolved after 2 seconds'); }, 2000); }); // Pause execution of the function until the delayPromise settles const result = await delayPromise; // This line will be executed after the delayPromise settles console.log(result); // Output: Resolved after 2 seconds } // Calling the async function asyncFunction();

Vishal Yelve · Answer

Hi Gomij, Do refer below links, which will help u to understand with examples https://www.freecodecamp.org/news/javascript-async-await/

Tuhin Paul · Answer

// Asynchronous function declared with async keyword async function asyncFunction() { return 'Hello from async function'; } // Calling the async function const resultPromise = asyncFunction(); // Handling the Promise returned by the async function resultPromise.then(result => { console.log(result); // Output: Hello from async function }); The async keyword is used to declare asynchronous functions. Async functions automatically return a Promise.

Tuhin Paul · Answer

Async/await builds upon Promises, which are objects representing the eventual completion (or failure) of an asynchronous operation. Promises have three states: pending, fulfilled (resolved), and rejected. // Function that returns a Promise resolving after a specified time function delay(ms) { return new Promise(resolve => { setTimeout(() => { resolve(`Promise resolved after ${ms} milliseconds`); }, ms); }); } // Using Promise with then/catch delay(2000) .then(message => { console.log(message); // This will be executed when the Promise is resolved }) .catch(error => { console.error(error); // This will be executed if the Promise is rejected }); // Using async/await async function runAsync() { try { const message = await delay(3000); // Wait for the Promise to be resolved console.log(message); // This will be executed when the Promise is resolved } catch (error) { console.error(error); // This will be executed if the Promise is rejected } } runAsync();

Md Sarfaraj · Answer

Please check out the video below. He explained everything very well. Link: https://www.youtube.com/watch?v=8aGhZQkoFbQ