ht_hooks/es/usePrevious/index.js

ht React 业务 Hooks

import { useRef } from 'react';
var defaultShouldUpdate = function (a, b) {
  return !Object.is(a, b);
}; //判断两值是否一致决定是否更新
function usePrevious(state, shouldUpdate) {
  if (shouldUpdate === void 0) {
    shouldUpdate = defaultShouldUpdate;
  }
  var prevRef = useRef(); //初始prevRef.current=undefined
  var curRef = useRef(); //初始curRef.current=undefined
  if (shouldUpdate(curRef.current, state)) {
    //初始初始curRef.current=undefined肯定不等于state，需要更新
    prevRef.current = curRef.current;
    curRef.current = state;
  }
  return prevRef.current;
}
export default usePrevious;