react-hooks

问题 When page loaded first time, I need to get all information, that is why I am calling a fetch request and set results into State [singleCall function doing that work] Along with that, I am connecting websocket using socket.io and listening to two events (odds_insert_one_two, odds_update_one_two), When I got notify event, I have to check with previous state and modify some content and update the state without calling again fetch request. But that previous state is still [] (Initial). How to get

问题 When page loaded first time, I need to get all information, that is why I am calling a fetch request and set results into State [singleCall function doing that work] Along with that, I am connecting websocket using socket.io and listening to two events (odds_insert_one_two, odds_update_one_two), When I got notify event, I have to check with previous state and modify some content and update the state without calling again fetch request. But that previous state is still [] (Initial). How to get

问题 I have the following code: import React, { useState, useEffect } from "react" function callSearchApi(userName: string, searchOptions: SearchOptions, searchQuery: string): Promise<SearchResult>{ return new Promise((resolve, reject) => { const searchResult = searchOptions.fooOption ? ["Foo 1", "Foo 2", "Foo 3"] : ["Bar 1", "Bar 2"] setTimeout(()=>resolve(searchResult), 3000) }) } type SearchOptions = { fooOption: boolean } type SearchResult = string[] export type SearchPageProps = { userName:

问题 I am building a multistep Form and I am trying to update my Data with the useState-Hook. Unfortunatly I do no how to pass the components of the hook as a prop, to update them, after performing an onClick Event Thats the important part of my code multisteform.js const defualtData = { Grundstück:'', Haus:"Haus", Wohnung:"Wohnung", Gewerbe:"Gewerbe", } const steps = [ {id: 'Häuser'}, {id: 'Fläche'}, {id: 'Grundstückerschlosse'}, {id: 'Bebauungsmöglichkeiten'} ] export const MultiStepFrom = () =>

问题 I have a custom hook called Api which fetches data from my API & handles my auth token and refresh tokens. On my Main app, there are multiple ways that my state variable "postId" will be changed. And whenever it is changed, I want my API to fetch the new content for that. But I can't call my custom Api within useEffect, which is how I'm detecting changes in postId. Can someone please suggest a workaround? I spent forever making this API, now I feel like I can't even use it. Main.tsx: import

问题 const { useState } = React; const App = () => { const [num, setNum] = useState(0); return ( <input type="number" value={num} onChange={(e)=>setNum(parseInt(e.target.value))} /> ) } ReactDOM.render(<App />, document.getElementById('root')); <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script> <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script> <div id="root" /> I want to keep num 's type as Number , not String . but

问题 const { useState } = React; const App = () => { const [num, setNum] = useState(0); return ( <input type="number" value={num} onChange={(e)=>setNum(parseInt(e.target.value))} /> ) } ReactDOM.render(<App />, document.getElementById('root')); <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script> <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script> <div id="root" /> I want to keep num 's type as Number , not String . but

问题 const { useState } = React; const App = () => { const [num, setNum] = useState(0); return ( <input type="number" value={num} onChange={(e)=>setNum(parseInt(e.target.value))} /> ) } ReactDOM.render(<App />, document.getElementById('root')); <script crossorigin src="https://unpkg.com/react@16/umd/react.development.js"></script> <script crossorigin src="https://unpkg.com/react-dom@16/umd/react-dom.development.js"></script> <div id="root" /> I want to keep num 's type as Number , not String . but

问题 I'm just starting to use react hooks and I'm having some issues when using custom hooks. It's probably lack of understanding but here's what I'm attempting My Custom hook: import React, { useState } from "react" export const useValidateContent = initState => { const[valid, setValid] = useState(initState) const[errorMsg, setErrorMsg] = useState(null) const validate = () => { // Update component state to test setValid(false) setErrorMsg('Some error found') } return [valid, validate, errorMsg] }

问题 I m having one sub child component which is inside a loop of parent component. when one of the sub child components is updating the state of parent component, it is re-rendering the all children since it is loop. How can i avoid the re-render for each iteration. It should update that particular sub child. import React, { useState } from "react"; function Parent() { const [selectedChild, setSelectedChild] = useState([]); const onChangeHandle = (event, id) => { const checked = event.target