//我想把它转换成一个函数钩子
componentDidMount（）{
const id = this.props.match.params.id;
getById( parseInt(id) )
.then(product => {
this.setState({
product,
loading: false
});
})
}
以下代码段等于类Component中的ComponentDidMount:
// ...
const [loading, setLoading] = React.useState(false);
const [product, setProduct] = React.useState(void 0);
React.useEffect(() => {
// Did mount, put your code here
setLoading(true)
// Fetch done
.then(product => {
setLoading(false)
setProduct(product)
})
}, []);
