JavaScript Async functions (async/await) Introduction
Example
A function defined as async is a function that can perform asynchronous actions but still look synchronous. The way it's done is using the await keyword to defer the function while it waits for a Promise to resolve or reject.
Note: Async functions are a Stage 4 ("Finished") proposal on track to be included in the ECMAScript 2017 standard.
For instance, using the promise-based Fetch API:
async function getJSON(url) {
try {
const response = await fetch(url);
return await response.json();
}
catch (err) {
// Rejections in the promise will get thrown here
console.error(err.message);
}
}
An async function always returns a Promise itself, so you can use it in other asynchronous functions.
Arrow function style
const getJSON = async url => {
const response = await fetch(url);
return await response.json();
}
