Search results
The await keyword can only be used inside an async function. The await keyword makes the function pause the execution and wait for a resolved promise before it continues: let value = await promise;
As stated earlier, await only works inside an async function. Let’s take the showAvatar () example from the chapter Promises chaining and rewrite it using async/await: We’ll need to replace .then calls with await. Also we should make the function async for them to work.
- Baseline Widely available
- Syntax
- Description
- Examples
- Browser compatibility
- See also
This feature is well established and works across many devices and browser versions. It’s been available across browsers since April 2017.
•Learn more
•See full compatibility
•Report feedback
The async function declaration creates a binding of a new async function to a given name. The await keyword is permitted within the function body, enabling asynchronous, promise-based behavior to be written in a cleaner style and avoiding the need to explicitly configure promise chains.
You can also define async functions using the async function expression.
Parameters
name The function's name. param Optional The name of a formal parameter for the function. For the parameters' syntax, see the Functions reference. statements Optional The statements comprising the body of the function. The await mechanism may be used.
An async function declaration creates an AsyncFunction object. Each time when an async function is called, it returns a new Promise which will be resolved with the value returned by the async function, or rejected with an exception uncaught within the async function.
Async functions can contain zero or more await expressions. Await expressions make promise-returning functions behave as though they're synchronous by suspending execution until the returned promise is fulfilled or rejected. The resolved value of the promise is treated as the return value of the await expression. Use of async and await enables the use of ordinary try / catch blocks around asynchronous code.
Async functions always return a promise. If the return value of an async function is not explicitly a promise, it will be implicitly wrapped in a promise.
For example, consider the following code:
It is similar to:
Note:
Async functions and execution order Rewriting a Promise chain with an async function
An API that returns a Promise will result in a promise chain, and it splits the function into many parts. Consider the following code: it can be rewritten with a single async function as follows: Alternatively, you can chain the promise with catch(): In the two rewritten versions, notice there is no await statement after the return keyword, although that would be valid too: The return value of an async function is implicitly wrapped in Promise.resolve - if it's not already a promise itself (as in the examples).
BCD tables only load in the browser with JavaScript enabled. Enable JavaScript to view data.
•Functions guide
•Using promises guide
•Functions
•AsyncFunction
•async function expression
•function
Dec 15, 2023 · Hello friends! In this article, I'm going to show you how to use the “async/await” special syntax when handling JavaScript Promises. If you don't know or need a refresher on JavaScript promises, you can read my previous article: How JavaScript Promises Work – Tutorial for Beginners.
Jan 19, 2023 · The async keyword. The first thing we need to do is label the containing function as being asynchronous. We can do this by using the async keyword, which we place in front of the function keyword ...
We want to make this open-source project available for people all around the world. Help to translate the content of this tutorial to your language!
People also ask
How to use async in JavaScript?
What is async/await in JavaScript?
How to create an asynchronous function in JavaScript?
Can I use async/await with just a function?
What does “async” mean before a function?
What is an async function declaration?
Nov 6, 2020 · getJobAsync('jobPositionHere') .then(data => console.log(data)); In the code above, we wrote an async function getJobAsync() that makes a fetch request to an external URL, next we awaited the response in a json format and then returned the data once the request is resolved. This is how to make an asynchronous request using asynchronous JavaScript.
