React的setState的callback问题 gongtiexin 61643564 发布于 2018-01-09 代码如下 render() { ... const columns = [ { title: "序号", dataIndex: "number", key: "number" }, { title: "用户ID", dataIndex: "category", key: "category", render: (text, record) => this.renderUserColumns(te...
export function useForceUpdate() { const handlers = useRef(new Set()).current; const [key, update] = useState(); useEffect(() => { handlers.forEach((h) => h()); handlers.clear(); }, [key]); return useCallback((callback) => { callback && handlers.add(callback); setState(s...
ps: 我们一直说的同步异步并不是指setState本身, setState本身一直一个同步函数, 我们指的是调用完setState后react会同步的去执行后续的步骤还是会异步的去执行后续的步骤. 结语 react官方做出这个改变其实也是为了更好的性能去考虑的, 毕竟调用完setState之后同步的进行渲染有时候会导致很多没必要的开销, 特别是在...
Component.prototype.setState=function(partialState,callback){invariant(typeofpartialState==='object'||typeofpartialState==='function'||partialState==null,'setState(...): takes an object of state variables to update or a '+'function which returns an object of state variables.',);this.updater...
Let’s start with the assumption that the setState method has been called. React adds the callback from setState to the updateQueue on the ClickCounter fiber node and schedules work. React enters the render phase. It starts traversing from the topmost HostRoot Fiber node using therenderRootfu...
在更新状态时,使用setState中的回调函数可以避免像过期状态这样的陷阱。与其这样做: 复制 // 风险:如果多个更新快速发生,可能会导致过期状态setCount(count+1); 1. 2. 使用更新器形式: 复制 setCount(prevCount=>prevCount+1); 1. 这确保您始终使用最新的状态值。
The SetStateAction returned from useState hook dose not accept a second callback argument. It cannot works like Class Componet's 'setState' method, which receives a callback param, and can perform the callback after this setState action updates; If the current behavior is a bug, please prov...
functionuseStateWithCallback(initialValue){const[state,setState]=useState(initialValue);// we need this flag for 2 reasons:// 1. To prevent the call on mount (first useEffect call)// 2. To force the effect to run when the state wasn't really updated// i.e next-state === previous-sta...
typeEffectCallback=()=>(void|Destructor); 1. 允许返回:undefined(空值)或清理函数 禁止返回:任何其他类型值(包括Promise) 这种设计是为了确保副作用(side effects)的清理工作能够正确执行。如果返回一个Promise,React无法正确处理这个Promise的完成状态,可能会导致内存泄漏或未预期的行为。
Notice that in ES6, we have a constructor() that we use to set the initial state,We can add default props and a display name as properties of the new class created, andThe render() method, which works as normal, but we’ve had to alter how we pass in the callback function. This...