declare an async function that will allow us to wait for other functions. we can only await inside an async function, and we can only await a promise.
Async/await is an ES2016 (ES7) feature, so you’ll need a transpiler. See http://babeljs.io/docs/plugins/preset-latest/
1npm i -g babel-cli
add a minimal .babelrc inside your project dir
1{
2 "presets": [
3 "latest"
4 ]
5}
and install packages (locally, inside your project folder)
1npm install --save-dev babel-preset-latest
Once setup, you can run from CLI
1babel-node script.js
We are going to use the JS builtin .fetch API for our example, but others like axios can also be used, any lib that returns a promise.
1npm i -D node-fetch
1import fetch form 'node-fetch'
2// Async/Await Example
3
4const service = {
5 getUsers: () => fetch('https://jsonplaceholder.typicode.com/users'),
6 getPosts: () => fetch('https://jsonplaceholder.typicode.com/posts')
7}
8
9// Await a promise to fulfill and do something
10async function Fetchy() {
11 try {
12 const users = await service.getUsers()
13 const posts = await service.getPosts()
14
15 console.log('Example: Fetchy', {
16 Users: users.data,
17 Posts: posts.data
18 })
19
20 } catch(err) {
21 console.warn('ERROR', err)
22 }
23}
24
25Fetchy()
26
27// Await all promises to fulfill
28async function FetchyAll() {
29 try {
30 const values = await Promise.all([ service.getUsers(), service.getPosts() ])
31 console.info('Example: FetchyAll', values.map(v => v.data))
32
33 } catch(err) {
34 console.warn(err)
35 }
36}
37
38FetchyAll()
You can only await on async functions from within other async functions.