useEffect 和 useRef

import { useEffect, useRef } from ‘react’;

export function usePrevious(value) {
const ref = useRef();
useEffect(() => {
ref.current = value;
}, [value]);
return ref.current;
}

// Usage
export function MyComponent(props) {
const { name } = props;
const previousName = usePrevious(name);

if(name != previousName) {
// Do something
}
}