We typically use constants to identify the type for the switch case (e.g. PET or COLOR) to avoid typos and to make it easier to change in the future if needed. import React, { useReducer } from 'react' import { render } from 'react-dom'...
一、useReducer const[state,dispatch]=useReducer(reducer,initialArg,init);// reducer 函数// initialArg state的初始值// init 惰性地创建初始 state ,特别适合用于有重置需求的场景 useReducer是useState的替代方案。它接收一个形如(state, action) => newState的 reducer,并返回当前的 state 以及与其配套的dispa...
functiondispatchReducerAction(fiber,queue,action){constupdate={action,next:null};constroot=enqueueConcurrentHookUpdate(fiber,queue,update);scheduleUpdateOnFiber(root);} ReactFiberConcurrentUpdates.js constconcurrentQueue=[];letconcurrentQueuesIndex=0;functionenqueueUpdate(fiber,queue,update){concurrentQueue[concu...
在React中使用useReducer Hook处理复杂的状态逻辑是一个很好的选择。useReducer是一个用于管理组件内部状态的Hook,可以用来替代useState来处理更复杂的状态逻辑。 下面是一个简单的示例,演示如何在React中使用useReducer来处理复杂的状态逻辑: importReact, { useReducer }from'react';constinitialState = {count:0, };fun...
https://www.react.express/hooks/usereducer useReducer By @msyleung The useReducer hook is similar to useState, but gives us a more structured approach for updating complex values. We typically use useReducer when our state has multiple sub-values, e.g. an object containing keys that we want ...
窗体控制输入中的React js useReducer钩子 React中的useReducer是一个React Hook,用于管理组件的状态和状态更新。它可以帮助开发者更好地组织和管理复杂的状态逻辑。 useReducer接受两个参数:reducer函数和初始状态。reducer函数接收当前状态和一个action对象作为参数,并返回新的状态。初始状态可以是任何类型的数据,如对象...
TheuseReducerHook returns the currentstateand adispatchmethod. Here is an example ofuseReducerin a counter app: Example:Get your own React.js Server import{useReducer}from"react";importReactDOMfrom"react-dom/client";constinitialTodos=[{id:1,title:"Todo 1",complete:false,},{id:2,title:"Todo...
React HOOK:useReducer useReducer 1.useReducer用最简单的话来说就是允许我们在函数组件里面像使用redux一样通过reducer和action来管理我们组件状态的变换 语法: const [state, dispatch] = useReducer(reducer, initialArg, init?)//useReducer和useState类似,都是用来管理组件状态的,只不过和useState的useReducer不一样...
3.在按钮中绑定点击事件,触发useReducer的事件需要使用dispatch,另外我们这里在函数中进行判断,如果action为add就累加1,否则返回state importReact, { useReducer }from'react'exportdefaultfunctionApp() {const[state, dispatch] =useReducer((state, action) =>{if(action ==='add') {returnstate+1}returnstate ...
最近在学习React,学到了React Hook 做了 useReducer Demo。 (二)介绍 使用useReducer是为了方便状态管理,用法和Redux特别像。 /* * @Author: ArdenZhao * @Date: 2022-04-18 17:26:35 * @LastEditTime: 2022-04-18 18:09:53 * @FilePath: /react-ts/src/components/react/10-Hook-useReducer.js ...