functionProfile({ userId }){// ✅ Good: comment包括其他的state在key改变时会自动的重置const[comment, setComment] = useState('');// ...} 通常,React在同一组件的同一个地方渲染时,React会保留状态。 四、当props改变时重置部分state 可能也有一些场景,比如说你只希望在props改变时,只修改部分的state,...
function updateState() { setIsOnline(navigator.onLine); } updateState(); window.addEventListener('online', updateState); window.addEventListener('offline', updateState); return () => { window.removeEventListener('online', updateState); window.removeEventListener('offline', updateState); }; },...
functionApp(){const[state,setState]=useState(0)useEffect(()=>{setInterval(()=>{console.log(state)// 一直是0},5000)},[])return{setCount(count+1)}}>test} 大家都知道是useEffect缺少state依赖项,只要加上[state]就可以正确输出更新后的state.但是为什么呢? 下面从源码角度,逐步看一下执行过程: 执...
所以你考虑用useEffect来清空state: export default function ProfilePage({ userId }) {const [comment, setComment] = useState('');// 🔴 Avoid: prop 改变时用useEffect来重置stateuseEffect(() => {setComment('');}, [userId]);// ...} 其实大家都可以感受得到,这个写法非常的低效且一看就不是正确...
== store.getState()) { subscription.notifyNestedSubs(); } return function () { subscription.tryUnsubscribe(); subscription.onStateChange = null; }; }, [contextValue, previousState]); var Context = context || ReactReduxContext; return React.createElement(Context.Provider, { value: context...
setState在useEffect钩子中不工作 、、、 我从我的firebase实时数据库中获取了一些数据,它在我的useEffect钩子函数中作为一个对象返回。我想在UI中将这些数据映射到不同的行中。我尝试将获取的数据对象转换为数组,然后设置状态,但console.log(状态)仍然显示一个空数组。当我使用状态作为依赖项(useEffect中的第二个参数...
Just like we did withAbortErrorinAbortController, Axios gives us a method calledisCancelthat allows us to check the cause of our errors and know how to handle them. If the request fails because the Axios source aborts or cancels, then we do not want to update the state. ...
我正在使用useNavigate钩子内的反应,以直接用户到主页成功登录后。我在网上所读到的一切都表明,我应该在一个useNavigate块内使用useEffect钩子,但是当我这样做时,它会触发一个无限循环:Warning: Maximum update depth exceeded. This can happen when a component calls setState inside useEffect, but useEffect either...
Next, open the browser and check the application. It will show the loading state and after 2 second, it will fetch the json and showcase the popular names as shown below −DOM mutationsThe useEffect hook can be used to manipulate the document using DOM and its methods. It makes sure ...
New state and initial state are the same so the theory about rerendering while the hook changed doesnt seem that possible, even though it could be due to the bug :) omaralsoudanii commented Sep 3, 2021 @Tosheen So did you check the examples I provided? Or did you stop when you ...