async-await.md

Async and Await in JavaScript

Async and Await in JavaScript Video

async and await are keywords in JavaScript that make it easier to work with asynchronous code. They are built on top of Promises and allow you to write asynchronous code that looks synchronous.

Async

The async keyword is used to declare an asynchronous function. An async function always returns a Promise. If the function returns a value, the Promise will be resolved with that value. If the function throws an error, the Promise will be rejected with that error.

async function fetchData() {
    return "Data fetched";
}

fetchData().then(data => console.log(data)); // Output: Data fetched

Await

The await keyword is used to wait for a Promise to resolve. It can only be used inside an async function. When the await keyword is used, the async function is paused until the Promise is resolved.

async function fetchData() {
    let promise = new Promise((resolve, reject) => {
        setTimeout(() => resolve("Data fetched"), 1000);
    });

    let result = await promise; // Wait until the promise resolves
    console.log(result); // Output: Data fetched
}

fetchData();

Example: Fetching Data from an API

Here is an example of using async and await to fetch data from an API:

async function getUserData() {
    try {
        let response = await fetch('https://jsonplaceholder.typicode.com/users/1');
        let data = await response.json();
        console.log(data);
    } catch (error) {
        console.error('Error fetching data:', error);
    }
}

getUserData();

In this example, the fetch function returns a Promise that resolves to a Response object. The await keyword is used to wait for the Promise to resolve, and then the json method is called on the Response object to get the data.

Conclusion

async and await make it easier to work with asynchronous code in JavaScript. They allow you to write code that looks synchronous, making it easier to read and maintain.