Async/Await is a new syntax for writing asynchronous code in JavaScript. Support was added in React Native 0.10 and it’s now reached TC39 stage 3 (candidate).
Example
In this example using the promise returning fetch polyfill. We will display the React Native GitHub star count.
const URL = "https://api.github.com/repos/facebook/react-native";
class StarCount extends Component {
constructor() {
super();
this.state = {stars: "?"};
}
componentDidMount() {
this.fetchData().done();
}
async fetchData() {
const response = await fetch(URL);
const json = await response.json();
const stars = json.stargazers_count;
this.setState({stars});
}
render() {
return (
<View style={styles.container}>
<Text style={styles.text}>
React Native has {this.state.stars} stars
</Text>
</View>
);
}
}
Async / await works with any Promise based API or one of your creation.
const getStars = () =>
new Promise(resolve => {
const FIVE_SECONDS = 5000;
// Simulate async operation
setTimeout(() => resolve(1234), FIVE_SECONDS);
});
const fetchData = async () => {
const stars = await getStars();
// Do something with stars
};
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