props参数传递(父传子)
javascript
//父组件
import React, { Component } from 'react'
import Child from './reac'
export default class index extends Component {
state={
data:[
{id:"001",name:"张三"},
{id:"002",name:"李四"},
{id:"003",name:"王五"},
]
}
render() {
return (
<div>
接受父组件传递过来的数据
<Child data={this.state.data}></Child>
</div>
)
}
}
//子组件
import React, { Component } from 'react'
export default class index extends Component {
render() {
console.log(this.props.data)
return (
<div>
<ul>
{
this.props.data.map((item)=>{
return <li key={item.id}>{item.name}</li>
})
}
</ul>
</div>
)
}
}
子组件传参给父组件(子传父)
javascript
//父组件
import React, { Component } from 'react'
import Child from './reac'
export default class index extends Component {
state={
name:""
}
getdata=(msg)=>{
this.setState({
name:msg
})
}
render() {
return (
<div>
接受子组件传递过来的数据{this.state.name}
<Child getdata={this.getdata}></Child>
</div>
)
}
}
//子组件
import React, { Component } from 'react'
export default class index extends Component {
render() {
return (
<div>
<button onClick={()=>{this.props.getdata("哈哈")}}>点击获取数据</button>
</div>
)
}
}
路由组件传递params参数 (父传子)
javascript
//父组件
import React, { Component } from 'react'
import {Link,Route} from 'react-router-dom'
import Detail from './Detail'
export default class Message extends Component {
state = {
messageArr:[
{id:'01',title:'消息1'},
{id:'02',title:'消息2'},
{id:'03',title:'消息3'},
]
}
render() {
const {messageArr} = this.state
return (
<div>
<ul>
{
messageArr.map((msgObj)=>{
return (
<li key={msgObj.id}>
{/* 向路由组件传递params参数 */}
<Link to={`/home/message/detail/${msgObj.id}/${msgObj.title}`}>{msgObj.title}</Link>
</li>
)
})
}
</ul>
<hr/>
{/* 声明接收params参数 */}
<Route path="/home/message/detail/:id/:title" component={Detail}/>
</div>
)
}
}
//子组件
import React, { Component } from 'react'
const DetailData = [
{id:'01',content:'张三'},
{id:'02',content:'李四'},
{id:'03',content:'王五'}
]
export default class Detail extends Component {
render() {
console.log(this.props);
// 接收params参数
const {id,title} = this.props.match.params
const findResult = DetailData.find((detailObj)=>{
return detailObj.id === id
})
return (
<ul>
<li>ID:{id}</li>
<li>TITLE:{title}</li>
<li>CONTENT:{findResult.content}</li>
</ul>
)
}
}
路由组件传递search参数(父传子)
javascript
//父组件
import React, { Component } from 'react'
import {Link,Route} from 'react-router-dom'
import Detail from './Detail'
export default class Message extends Component {
state = {
messageArr:[
{id:'01',title:'消息1'},
{id:'02',title:'消息2'},
{id:'03',title:'消息3'},
]
}
render() {
const {messageArr} = this.state
return (
<div>
<ul>
{
messageArr.map((msgObj)=>{
return (
<li key={msgObj.id}>
{/* 向路由组件传递search参数 */}
<Link to={`/home/message/detail/?id=${msgObj.id}&title=${msgObj.title}`}>{msgObj.title}</Link>
</li>
)
})
}
</ul>
<hr/>
{/* search参数无需声明接收,正常注册路由即可 */}
<Route path="/home/message/detail" component={Detail}/>
</div>
)
}
}
//子组件
import React, { Component } from 'react'
import qs from 'querystring'
const DetailData = [
{id:'01',content:'张三'},
{id:'02',content:'李四'},
{id:'03',content:'王五'}
]
export default class Detail extends Component {
render() {
console.log(this.props);
// 接收search参数
const {search} = this.props.location
const {id,title} = qs.parse(search.slice(1))
const findResult = DetailData.find((detailObj)=>{
return detailObj.id === id
})
return (
<ul>
<li>ID:{id}</li>
<li>TITLE:{title}</li>
<li>CONTENT:{findResult.content}</li>
</ul>
)
}
}
路由组件传递state参数(父传子)
javascript
//父组件
import React, { Component } from 'react'
import {Link,Route} from 'react-router-dom'
import Detail from './Detail'
export default class Message extends Component {
state = {
messageArr:[
{id:'01',title:'消息1'},
{id:'02',title:'消息2'},
{id:'03',title:'消息3'},
]
}
render() {
const {messageArr} = this.state
return (
<div>
<ul>
{
messageArr.map((msgObj)=>{
return (
<li key={msgObj.id}>
{/* 向路由组件传递state参数 */}
<Link to={{pathname:'/home/message/detail',state:{id:msgObj.id,title:msgObj.title}}}>{msgObj.title}</Link>
</li>
)
})
}
</ul>
<hr/>
{/* state参数无需声明接收,正常注册路由即可 */}
<Route path="/home/message/detail" component={Detail}/>
</div>
)
}
}
//子组件
import React, { Component } from 'react'
// import qs from 'querystring'
const DetailData = [
{id:'01',content:'你好,中国'},
{id:'02',content:'你好,尚硅谷'},
{id:'03',content:'你好,未来的自己'}
]
export default class Detail extends Component {
render() {
console.log(this.props);
// 接收state参数
const {id,title} = this.props.location.state || {}
const findResult = DetailData.find((detailObj)=>{
return detailObj.id === id
}) || {}
return (
<ul>
<li>ID:{id}</li>
<li>TITLE:{title}</li>
<li>CONTENT:{findResult.content}</li>
</ul>
)
}
}
路由的其本知识点(react-router6)
1,一级路由
javascript
//父元素
import React from 'react'
import {NavLink,Routes,Route} from 'react-router-dom'
import About from './pages/About'
import Home from './pages/Home'
export default function App() {
return (
<div>
<div className="row">
<div className="col-xs-offset-2 col-xs-8">
<div className="page-header"><h2>React Router Demo</h2></div>
</div>
</div>
<div className="row">
<div className="col-xs-2 col-xs-offset-2">
<div className="list-group">
{/* 路由链接 */}
<NavLink className="list-group-item" to="/about">About</NavLink>
<NavLink className="list-group-item" to="/home">Home</NavLink>
</div>
</div>
<div className="col-xs-6">
<div className="panel">
<div className="panel-body">
{/* 注册路由 */}
<Routes>
<Route path="/about" element={<About/>}/>
<Route path="/home" element={<Home/>}/>
</Routes>
</div>
</div>
</div>
</div>
</div>
)
}
//两上要接受的子元素 about和Home
import React from 'react'
export default function About() {
return (
<h3>我是About的内容</h3>
)
}
import React from 'react'
export default function Home() {
return (
<h3>我是Home的内容</h3>
)
}
2,重定向
javascript
//父组件
import React from 'react'
import {NavLink,Routes,Route,Navigate} from 'react-router-dom'
import About from './pages/About'
import Home from './pages/Home'
export default function App() {
return (
<div>
<div className="row">
<div className="col-xs-offset-2 col-xs-8">
<div className="page-header"><h2>React Router Demo</h2></div>
</div>
</div>
<div className="row">
<div className="col-xs-2 col-xs-offset-2">
<div className="list-group">
{/* 路由链接 */}
<NavLink className="list-group-item" to="/about">About</NavLink>
<NavLink className="list-group-item" to="/home">Home</NavLink>
</div>
</div>
<div className="col-xs-6">
<div className="panel">
<div className="panel-body">
{/* 注册路由 */}
<Routes>
<Route path="/ABOUT" element={<About/>}/>
<Route path="/home" element={<Home/>}/>
<Route path="/" element={<Navigate to="/about"/>}/>
</Routes>
</div>
</div>
</div>
</div>
</div>
)
}
//about和home
import React from 'react'
export default function About() {
return (
<h3>我是About的内容</h3>
)
}
import React,{useState} from 'react'
import {Navigate} from 'react-router-dom'
export default function Home() {
const [sum,setSum] = useState(1)
return (
<div>
<h3>我是Home的内容</h3>
{sum === 2 ? <Navigate to="/about" replace={true}/> : <h4>当前sum的值是:{sum}</h4>}
<button onClick={()=>setSum(2)}>点我将sum变为2</button>
</div>
)
}
3,react导航高亮
javascript
//父元素 这里的样式reactStyle需要提前声明
import React from 'react'
//引入路由
import {NavLink,Routes,Route,Navigate} from 'react-router-dom'
//引入组件
import About from './Pages/About'
import Home from './Pages/Home'
export default function App() {
function computetClassStyle({isActive}){
return isActive?'list-group-item reactStyle':'list-group-item'
}
return (
<div>
<div>
<div className="row">
<div className="col-xs-offset-2 col-xs-8">
<div className="page-header"><h2>React Router Demo</h2></div>
</div>
</div>
<div className="row">
<div className="col-xs-2 col-xs-offset-2">
<div className="list-group">
<NavLink className={computetClassStyle} to="about">About</NavLink>
<NavLink className={computetClassStyle} to="/home">Home</NavLink>
</div>
</div>
<div className="col-xs-6">
<div className="panel">
<div className="panel-body">
<h3>新路由</h3>
{/* 注册路由 */}
<Routes>
<Route path='/About' element={<About></About>}></Route>
<Route path='/Home' element={<Home></Home>}></Route>
<Route path='/' element={<Navigate to="/About"></Navigate>}></Route>
</Routes>
</div>
</div>
</div>
</div>
</div>
</div>
)
}
//两上要接受的子元素 about和Home
import React from 'react'
export default function About() {
return (
<h3>我是About的内容</h3>
)
}
import React from 'react'
export default function Home() {
return (
<h3>我是Home的内容</h3>
)
}
4,路由的统一管理
javascript
//在主文件中使用
import React from 'react'
//引入路由
import {NavLink,useRoutes} from 'react-router-dom'
import router from './router'
export default function App() {
//路由表的使用
const element=useRoutes(router)
return (
<div>
<div>
<div className="row">
<div className="col-xs-offset-2 col-xs-8">
<div className="page-header"><h2>React Router Demo</h2></div>
</div>
</div>
<div className="row">
<div className="col-xs-2 col-xs-offset-2">
<div className="list-group">
<NavLink className="list-group-item" to="about">About</NavLink>
<NavLink className="list-group-item" to="/home">Home</NavLink>
</div>
</div>
<div className="col-xs-6">
<div className="panel">
<div className="panel-body">
<h3>新路由</h3>
{/* 注册路由 */}
{element}
</div>
</div>
</div>
</div>
</div>
</div>
)
}
//router中的路由列表
import Home from "../Pages/Home"
import About from "../Pages/About"
import { Navigate } from "react-router-dom"
export default [
{
path:'/about',
element:<About></About>
},
{
path:'/Home',
element:<Home></Home>
},
{
path:'/',
element:<Navigate to="/about"></Navigate>
}
]
5,路由的嵌套,父里面包含子
6,search传递参数
javascript
//参数传递组件
import React,{useState} from 'react'
import { Link,Outlet } from 'react-router-dom'
export default function Message() {
const [message] =useState([
{id:'001',title:'张三',content:'kdjfkdfj'},
{id:'002',title:'李四',content:'45612'},
{id:'003',title:'王五',content:'kdjferetdkdfj'},
{id:'004',title:'赵六',content:'kdjadffkdfj'}
])
return (
<div>
<ul>
{
message.map((m)=>{
return (
<li key={m.id}>
{/* 使用search带参数 */}
<Link to={`detail?id=${m.id}&title=${m.title}&content=${m.content}`}>{m.title}</Link>
</li>
)
})
}
</ul>
{/* 规定路由展示的位置 */}
<Outlet></Outlet>
</div>
)
}
//参数接收组件
import React from 'react'
import { useSearchParams } from 'react-router-dom'
export default function Detail() {
const [search]=useSearchParams()
console.log(search.get('id'))
const id=search.get('id')
const title=search.get('title')
const content=search.get('content')
return (
<div>
<ul>
<li>{id}</li>
<li>{title}</li>
<li>{content}</li>
</ul>
</div>
)
}
7,state传递参数
javascript
//传递组件
import React,{useState} from 'react'
import { Link,Outlet } from 'react-router-dom'
export default function Message() {
const [message] =useState([
{id:'001',title:'张三',content:'kdjfkdfj'},
{id:'002',title:'李四',content:'45612'},
{id:'003',title:'王五',content:'kdjferetdkdfj'},
{id:'004',title:'赵六',content:'kdjadffkdfj'}
])
return (
<div>
<ul>
{
message.map((m)=>{
return (
<li key={m.id}>
{/* 使用state带参数 state里面需要包含一个对象*/}
<Link to="detail" state={{
id:m.id,
title:m.title,
content:m.content
}}>{m.title}</Link>
</li>
)
})
}
</ul>
{/* 规定路由展示的位置 */}
<Outlet></Outlet>
</div>
)
}
//接受组件
import React from 'react'
//需要使用useLocation
import { useLocation } from 'react-router-dom'
export default function Detail() {
const {state:{id,title,content}}=useLocation()
return (
<div>
<ul>
<li>{id}</li>
<li>{title}</li>
<li>{content}</li>
</ul>
</div>
)
}
8,编程式路由导航
javascript
//传递组件
import React,{useState} from 'react'
import { Link,Outlet,useNavigate } from 'react-router-dom'
export default function Message() {
const [message] =useState([
{id:'001',title:'张三',content:'kdjfkdfj'},
{id:'002',title:'李四',content:'45612'},
{id:'003',title:'王五',content:'kdjferetdkdfj'},
{id:'004',title:'赵六',content:'kdjadffkdfj'}
])
//编辑式路由导航,需要借助useNavigate
//2,useNavigate还可以实现前进和后退 传入对应的参数即可
const Nav=useNavigate()
function showDetail(m){
Nav('Detail',{
replace:false,
state:{
id:m.id,
title:m.title,
content:m.content
}
})
}
return (
<div>
<ul>
{
message.map((m)=>{
return (
<li key={m.id}>
{/* 使用state带参数 state里面需要包含一个对象*/}
<Link to="detail" state={{
id:m.id,
title:m.title,
content:m.content
}}>{m.title}</Link>
<button onClick={()=>showDetail(m)}>查看详情</button>
</li>
)
})
}
</ul>
{/* 规定路由展示的位置 */}
<Outlet></Outlet>
</div>
)
}
//接受组件
import React from 'react'
//需要使用useLocation
import { useLocation } from 'react-router-dom'
export default function Detail() {
const {state:{id,title,content}}=useLocation()
return (
<div>
<ul>
<li>{id}</li>
<li>{title}</li>
<li>{content}</li>
</ul>
</div>
)
}
setState更新状态的2种写法
(1). setState(stateChange, [callback])------对象式的setState
1.stateChange为状态改变对象(该对象可以体现出状态的更改)
2.callback是可选的回调函数, 它在状态更新完毕、界面也更新后(render调用后)才被调用
(2). setState(updater, [callback])------函数式的setState
1.updater为返回stateChange对象的函数。
2.updater可以接收到state和props。
4.callback是可选的回调函数, 它在状态更新、界面也更新后(render调用后)才被调用。
总结:
1.对象式的setState是函数式的setState的简写方式(语法糖)
2.使用原则:
(1).如果新状态不依赖于原状态 ===> 使用对象方式
(2).如果新状态依赖于原状态 ===> 使用函数方式
(3).如果需要在setState()执行后获取最新的状态数据,
要在第二个callback函数中读取
javascript
//父组件 App.js
//import logo from './logo.svg';
import React, { Component } from 'react'
import './App.css'
import SetStateA from './components/SetState1'
export default class App extends Component{
render(){
return(
<div>
<SetStateA></SetStateA>
</div>
)
}
}
//子组件 components
import React, { Component } from 'react'
export default class SetStateA extends Component {
//对象式的setState
state={count:0}
add=()=>{
//获取原来count的值
const {count}=this.state
//更新状态
this.setState({count:count+1},()=>{
console.log('监测值的改变'+this.state.count)
})
}
//函数式的写法
addNum=()=>{
this.setState((state,props)=>{
console.log(props)
return {count:state.count+1}
})
}
render() {
return (
<div>
<h1>当前求和为{this.state.count}</h1>
<button onClick={this.add}>对象式</button>
<button onClick={this.addNum}>函数式</button>
</div>
)
}
}
路由组件的lazyLoad
1,lazyLoad主要用于大量路由切换的时候,根据需要加载对应的路由信息
2,通过React的lazy函数配合import()函数动态加载路由组件 ===> 路由组件代码会被分开打包
3,通过<Suspense>指定在加载得到路由
javascript
//在父组件App.js中引入子组件
//import logo from './logo.svg';
import React, { Component } from 'react'
import './App.css'
import Lazyload from './components/Layload'
export default class App extends Component{
render(){
return(
<div>
<Lazyload></Lazyload>
</div>
)
}
}
//lazyload组件里面包含两个子组件home和about
import React, { Component,lazy,Suspense } from 'react'
import {NavLink,Route} from 'react-router-dom'
//以前的加载方式
// import Home from './Home'
// import About from './About'
//使用lazy
const Home=lazy(()=>import('./Home'))
const About =lazy(()=>import('./About'))
export default class Lazyload extends Component {
render() {
return (
<div>
<div className="row">
<div className="col-xs-offset-2 col-xs-8">
<div className="page-header"><h2>React Router</h2></div>
</div>
</div>
<div className="row">
<div className="col-xs-2 col-xs-offset-2">
<div className="list-group">
{/* 在React中靠路由链接实现切换组件--编写路由链接 */}
<NavLink className="list-group-item" to="/About">About</NavLink>
<NavLink className="list-group-item" to="/Home">Home</NavLink>
</div>
</div>
<div className="col-xs-6">
<div className="panel">
<div className="panel-body">
{/* 注册路由 */}
<Suspense fallback={<h1>正在加载中......</h1>}>
<Route path="/About" component={About}/>
<Route path="/Home" component={Home}/>
</Suspense>
</div>
</div>
</div>
</div>
</div>
)
}
}
//about和home两个子组件中的内容
//about
import React, { Component } from 'react'
export default class About extends Component {
render() {
return (
<div>
About
</div>
)
}
}
//home
import React, { Component } from 'react'
export default class Home extends Component {
render() {
return (
<div>
Home
</div>
)
}
}
State Hook
(1). State Hook让函数组件也可以有state状态, 并进行状态数据的读写操作
(2). 语法: const [xxx, setXxx] = React.useState(initValue)
(3). useState()说明:
参数: 第一次初始化指定的值在内部作缓存
返回值: 包含2个元素的数组, 第1个为内部当前状态值, 第2个为更新状态值的函数
(4). setXxx()2种写法:
setXxx(newValue): 参数为非函数值, 直接指定新的状态值, 内部用其覆盖原来的状态值
setXxx(value => newValue): 参数为函数, 接收原本的状态值, 返回新的状态值, 内部用其覆盖原来的状态值
javascript
//app.js
import React, { Component } from 'react'
import './App.css'
import SetStateA from './components/Hooks'
export default class App extends Component{
render(){
return(
<div>
<SetStateA></SetStateA>
</div>
)
}
}
//函数式子组件
import React from 'react'
//函数式组件的
function Demo(){
const [count,setCount] = React.useState(0)
const [name,setName]=React.useState('张三')
//console.log(count,setCount)
function add(){
console.log("点击事件")
//setCount(count+1)//第一种写法
//第二种写法
setCount((count)=>{
return count+1
})
}
function changeName(){
setName("李四")
}
return (
<div>
<h2>当前求和为{count}</h2>
<h2>名字是{name}</h2>
<button onClick={add}>加1</button>
<button onClick={changeName}>点我改名字</button>
</div>
)
}
export default Demo
Ref Hook
(1). Ref Hook可以在函数组件中存储/查找组件内的标签或任意其它数据
(2). 语法: const refContainer = useRef()
javascript
//父组件
import React, { Component } from 'react'
import './App.css'
import SetStateA from './components/Hooks'
export default class App extends Component{
render(){
return(
<div>
<SetStateA></SetStateA>
</div>
)
}
}
//子组件
import React from 'react'
//函数式组件的
function Demo(){
const myRef = React.useRef()
function show(){
alert(myRef.current.value)
}
return (
<div>
<input type="text" ref={myRef} />
<button onClick={show}>点我提示</button>
</div>
)
}
export default Demo
Fragment
可用于取代一个真实的DOM根标签
javascript
import React, { Component,Fragment } from 'react'
export default class FragMent extends Component {
render() {
return (
<Fragment>
<input type="text" />
<button>点击</button>
</Fragment>
)
}
}
Component
> 1. 只要执行setState(),即使不改变状态数据, 组件也会重新render() ==> 效率低
>
> 2. 只当前组件重新render(), 就会自动重新render子组件,纵使子组件没有用到父组件的任何数据 ==> 效率低
效率高的做法
> 只有当组件的state或props数据发生改变时才重新render()
原因
> Component中的shouldComponentUpdate()总是返回true
解决
办法1:
重写shouldComponentUpdate()方法
比较新旧state或props数据, 如果有变化才返回true, 如果没有返回false
办法2:
使用PureComponent
PureComponent重写了shouldComponentUpdate(), 只有state或props数据有变化才返回true
注意:
只是进行state和props数据的浅比较, 如果只是数据对象内部数据变了, 返回false
不要直接修改state数据, 而是要产生新数据
项目中一般使用PureComponent来优化
render props(向组件内部动态传入带内容的结构)
Vue中:
使用slot技术, 也就是通过组件标签体传入结构 <A><B/></A>
React中:
使用children props: 通过组件标签体传入结构
使用render props: 通过组件标签属性传入结构,而且可以携带数据,一般用render函数属性
children props
<A>
<B>xxxx</B>
</A>
{this.props.children}
问题: 如果B组件需要A组件内的数据, ==> 做不到
render props
<A render={(data) => <C data={data}></C>}></A>
A组件: {this.props.render(内部state数据)}
C组件: 读取A组件传入的数据显示 {this.props.data}
javascript
//父组件
import React, { Component } from 'react'
import './App.css'
import SetStateA from './components/RenderProps'
export default class App extends Component{
render(){
return(
<div>
<SetStateA></SetStateA>
</div>
)
}
}
//子组件 父组件中包含子组件的子组件,并实现传递数据
import React, { Component } from 'react'
import './index.css'
export default class Parent extends Component {
render() {
return (
<div className='parent'>
<h3>我是props样式</h3>
<h4>这是父组件里面又包含了一个子组件</h4>
<A render={(name)=><B name={name}/>}/>
</div>
)
}
}
class A extends Component{
state={name:"张三"}
render(){
const {name} = this.state
return(
<div className='a'>
<h3>我是A组件</h3>
<h4>{this.props.render(name)}</h4>
</div>
)
}
}
class B extends Component{
render(){
return(
<div className='b'>
<h3>我是B组件{this.props.name}</h3>
</div>
)
}
}
错误边界
1,错误边界(Error boundary):用来捕获后代组件错误,渲染出备用页面
2,只能捕获后代组件生命周期产生的错误,不能捕获自己组件产生的错误和其他组件在合成事件、定时器中产生的错误
3,使用方式getDerivedStateFromError
javascript
//父组件
import React, { Component } from 'react'
import './App.css'
import SetStateA from './components/ErrorDer'
export default class App extends Component{
render(){
return(
<div>
<SetStateA></SetStateA>
</div>
)
}
}
//子组件里面包含子组件
import React, { Component } from 'react'
import Child from './child'
export default class index extends Component {
//用于标识子组件是否产生错误
state={
hasError:""
}
static getDerivedStateFromError(error){
console.log("@@@",error)
return {hasError:error}
}
//用于子组件会出现的问题,在父组件提交做预判
render() {
return (
<div>
{this.state.hasError?<h2>请稍后在试吧</h2>:<Child></Child>}
</div>
)
}
}
//child组件
import React, { Component } from 'react'
export default class index extends Component {
//对应的子组件里面出现的错误
state={
// users:[
// {id:"01",name:"张三"},
// {id:"02",name:"李四"},
// {id:"03",name:"王五"}
// ]
users:'张三'
}
//只能处理生命周期里面处理的错误 一般用于处理render里面出现的错误
render() {
return (
<div>
<h2>我是子组件</h2>
{
this.state.users.map((userObj)=>{
return <h3 key={userObj.id}>{userObj.name}</h3>
})
}
</div>
)
}
}
组件通信方式总结
1,组件间的关系:
-
父子组件
-
兄弟组件(非嵌套组件)
-
祖孙组件(跨级组件)
2,几种通信方式:
1.props:
(1).children props
(2).render props
2.消息订阅-发布:
pubs-sub
3.集中式管理:
redux
4.conText:
生产者-消费者模式
3, 比较好的搭配方式:
父子组件:props
兄弟组件:消息订阅-发布、集中式管理
祖孙组件(跨级组件):消息订阅-发布、集中式管理、conText(开发用的少,封装插件用的多)