React 16.8 方法是通过改变父组件传给子组件的值会使子组件重新render触发子组件的useEffect事件

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父组件   import React, { useState } from 'react' import Child from './index.js'    function Father () {     const [toChildNum, setToChildNum] = useState(0)        return (         <div>             <button                 onPress={() => {                     setToChildNum(toChildNum + 1)                 }}             >                 点击调用子组件方法             </button>             <Child num={toChildNum} />         </div>     ) }    export default Father;<br> 子组件   import React, { useEffect } from 'react'    function Child ({ num }) {        useEffect(() => {         alert('我被调用了')     }, [num])        return  (         <div>子组件</div>     ) }