问用forwardRef和useRef无法读取ref的null属性ENuseRef 是 react 中的一个 hooks，用于管理函数组件中引用...
react新增的钩子API，目的是增加代码的可复用性，逻辑性，弥补无状态组件没有生命周期，没有数据管理状态...
改动的时候需要调用函数，而且带来很多其他限制和代价（比如必须要给useEffect传递正确的依赖数组，不然回调...
const Parent = () => {const childRef = useRef(null)useEffect(()=>{chilRef.current.sayName();// child})return<Child ref={childRef}/>}const Child = forwardRef((props,ref) => {useImperativeHandle(ref,()=>({sayName:()=>{console.log('child')}}))returnChild}} 1. 2. 3. 4. 5....
这段代码会在组件挂载后自动计算距离窗口顶部的距离,并设置滚动条位置使其距离顶部50px。注意要在 useEffect 的依赖项数组中传入一个空数组,以确保只执行一次。 请注意,由于不同机型的视口高度可能不同,可能需要根据实际情况微调windowHeight - signinTop + 50中的数值来适应不同机型。
{ const innerRef = useRef(null); useEffect(() => { if (!ref) return; if (typeof ref === 'function') { ref(innerRef.current); } else { ref.current = innerRef.current; } }); return innerRef;}export const MyTextField = React.forwardRef((props, ref) => { const forwardedRef ...
Another solution to the “object might be null” error with refs in React is to use the not null (!) assertion operator. import{useEffect, useRef}from'react';exportdefaultfunctionApp(){constinputRef = useRef<HTMLInputElement>(null);useEffect(()=>{// 👇️ using non-null (!) assertion...
{ const innerRef = useRef(null); useEffect(() => { if (!ref) return; if (typeof ref === 'function') { ref(innerRef.current); } else { ref.current = innerRef.current; } }); return innerRef;}export const MyTextField = React.forwardRef((props, ref) => { const forwardedRef ...
It’s important to note that when you change the value of the current property of ref, it won’t cause a re-render, so we don’t have touseEffectadd it in the dependencies. The key time to get the height of an element using a ref isuseEffectto do it in the hook, after the ref...
React ref current is NULL Why is the ref current null when using useeffect? How to check if a myref is null? Is it possible to get the current DOM element in react-createref? Do I need to use React-createref ()? React ref.current is null ...