react脚手架运用

3.1. 使用create-react-app创建react应用

3.1.1. react脚手架

1.xxx脚手架: 用来帮助程序员快速创建一个基于xxx库的模板项目
1.包含了所有需要的配置（语法检查、jsx编译、devServer…）
2.下载好了所有相关的依赖
3.可以直接运行一个简单效果

2.react提供了一个用于创建react项目的脚手架库: create-react-app
3.项目的整体技术架构为: react + webpack + es6 + eslint
4.使用脚手架开发的项目的特点: 模块化, 组件化, 工程化

3.1.2. 创建项目并启动

第一步，全局安装：npm i -g create-react-app
第二步，切换到想创项目的目录，使用命令：create-react-app hello-react
第三步，进入项目文件夹：cd hello-react
第四步，启动项目：npm start

小例子：

index.js

import React from 'react';
import ReactDOM from 'react-dom';
import App from './App';

ReactDOM.render(
  
    <App />,
  document.getElementById('root')
);

App.js

//创建“外壳”组件App
import React,{Component} from 'react'
import Hello from './components/Hello'
import Welcome from './components/Welcome'

export default class App extends Component{
	render(){
		return(
		    <div>
			    <Hello></Hello>
				<Welcome></Welcome>
			</div>
		)
	}
}

index.jsx

import React,{Component} from 'react'
import hello from './index.module.css'

export default class Hello extends Component{
	render(){
		return <h2 className={hello.title}>Hello,React!</h2>
	}
}

另外一个

import React,{Component} from 'react'
import './index.css'

export default class Welcome extends Component{
	render(){
		return <h2 className="title">Welcome</h2>
	}
}

样式自己写

3.1.3. react脚手架项目结构

public ---- 静态资源文件夹
favicon.icon ------ 网站页签图标
index.html -------- 主页面
logo192.png ------- logo图
logo512.png ------- logo图
manifest.json ----- 应用加壳的配置文件
robots.txt -------- 爬虫协议文件
src ---- 源码文件夹
App.css -------- App组件的样式
App.js --------- App组件
App.test.js ---- 用于给App做测试
index.css ------ 样式
index.js ------- 入口文件
logo.svg ------- logo图
reportWebVitals.js
— 页面性能分析文件(需要web-vitals库的支持)
setupTests.js
---- 组件单元测试的文件(需要jest-dom库的支持)

样式重叠可以使用下面这种方式：

import React,{Component} from 'react'
import hello from './index.module.css'

export default class Hello extends Component{
	render(){
		return <h2 className={hello.title}>Hello,React!</h2>
	}
}

TodoList案例

App.jsx

import React, { Component } from 'react'
import Header from './components/Header'
import List from './components/List'
import Footer from './components/Footer'
import './App.css'

export default class App extends Component {
	//状态在哪里，操作状态的方法就在哪里

	//初始化状态
	state = {todos:[
		{id:'001',name:'吃饭',done:true},
		{id:'002',name:'睡觉',done:true},
		{id:'003',name:'打代码',done:false},
		{id:'004',name:'逛街',done:false}
	]}

	//addTodo用于添加一个todo，接收的参数是todo对象
	addTodo = (todoObj)=>{
		//获取原todos
		const {todos} = this.state
		//追加一个todo
		const newTodos = [todoObj,...todos]
		//更新状态
		this.setState({todos:newTodos})
	}

	//updateTodo用于更新一个todo对象
	updateTodo = (id,done)=>{
		//获取状态中的todos
		const {todos} = this.state
		//匹配处理数据
		const newTodos = todos.map((todoObj)=>{
			if(todoObj.id === id) return {...todoObj,done}
			else return todoObj
		})
		this.setState({todos:newTodos})
	}

	//deleteTodo用于删除一个todo对象
	deleteTodo = (id)=>{
		//获取原来的todos
		const {todos} = this.state
		//删除指定id的todo对象
		const newTodos = todos.filter((todoObj)=>{
			return todoObj.id !== id
		})
		//更新状态
		this.setState({todos:newTodos})
	}

	//checkAllTodo用于全选
	checkAllTodo = (done)=>{
		//获取原来的todos
		const {todos} = this.state
		//加工数据
		const newTodos = todos.map((todoObj)=>{
			return {...todoObj,done}
		})
		//更新状态
		this.setState({todos:newTodos})
	}

	//clearAllDone用于清除所有已完成的
	clearAllDone = ()=>{
		//获取原来的todos
		const {todos} = this.state
		//过滤数据
		const newTodos = todos.filter((todoObj)=>{
			return !todoObj.done
		})
		//更新状态
		this.setState({todos:newTodos})
	}

	render() {
		const {todos} = this.state
		return (
			<div className="todo-container">
				<div className="todo-wrap">
					<Header addTodo={this.addTodo}/>
					<List todos={todos} updateTodo={this.updateTodo} deleteTodo={this.deleteTodo}/>
					<Footer todos={todos} checkAllTodo={this.checkAllTodo} clearAllDone={this.clearAllDone}/>
				</div>
			</div>
		)
	}
}

Header.jsx

import React, { Component } from 'react'
import PropTypes from 'prop-types'
import {nanoid} from 'nanoid'
import './index.css'

export default class Header extends Component {

	//对接收的props进行：类型、必要性的限制
	static propTypes = {
		addTodo:PropTypes.func.isRequired
	}

	//键盘事件的回调
	handleKeyUp = (event)=>{
		//解构赋值获取keyCode,target
		const {keyCode,target} = event
		//判断是否是回车按键
		if(keyCode !== 13) return
		//添加的todo名字不能为空
		if(target.value.trim() === ''){
			alert('输入不能为空')
			return
		}
		//准备好一个todo对象
		const todoObj = {id:nanoid(),name:target.value,done:false}
		//将todoObj传递给App
		this.props.addTodo(todoObj)
		//清空输入
		target.value = ''
	}

	render() {
		return (
			<div className="todo-header">
				<input onKeyUp={this.handleKeyUp} type="text" placeholder="请输入你的任务名称，按回车键确认"/>
			</div>
		)
	}
}

list.jsx

import React, { Component } from 'react'
import PropTypes from 'prop-types'
import Item from '../Item'
import './index.css'

export default class List extends Component {

	//对接收的props进行：类型、必要性的限制
	static propTypes = {
		todos:PropTypes.array.isRequired,
		updateTodo:PropTypes.func.isRequired,
		deleteTodo:PropTypes.func.isRequired,
	}

	render() {
		const {todos,updateTodo,deleteTodo} = this.props
		return (
			<ul className="todo-main">
				{
					todos.map( todo =>{
						return <Item key={todo.id} {...todo} updateTodo={updateTodo} deleteTodo={deleteTodo}/>
					})
				}
			</ul>
		)
	}
}

item.jsx

import React, { Component } from 'react'
import './index.css'

export default class Item extends Component {

	state = {mouse:false} //标识鼠标移入、移出

	//鼠标移入、移出的回调
	handleMouse = (flag)=>{
		return ()=>{
			this.setState({mouse:flag})
		}
	}

	//勾选、取消勾选某一个todo的回调
	handleCheck = (id)=>{
		return (event)=>{
			this.props.updateTodo(id,event.target.checked)
		}
	}

	//删除一个todo的回调
	handleDelete = (id)=>{
		if(window.confirm('确定删除吗？')){
			this.props.deleteTodo(id)
		}
	}


	render() {
		const {id,name,done} = this.props
		const {mouse} = this.state
		return (
			<li style={{backgroundColor:mouse ? '#ddd' : 'white'}} onMouseEnter={this.handleMouse(true)} onMouseLeave={this.handleMouse(false)}>
				<label>
					<input type="checkbox" checked={done} onChange={this.handleCheck(id)}/>
					<span>{name}</span>
				</label>
				<button onClick={()=> this.handleDelete(id) } className="btn btn-danger" style={{display:mouse?'block':'none'}}>删除</button>
			</li>
		)
	}
}

footer.jsx

import React, { Component } from 'react'
import './index.css'

export default class Footer extends Component {

	//全选checkbox的回调
	handleCheckAll = (event)=>{
		this.props.checkAllTodo(event.target.checked)
	}

	//清除已完成任务的回调
	handleClearAllDone = ()=>{
		this.props.clearAllDone()
	}

	render() {
		const {todos} = this.props
		//已完成的个数
		const doneCount = todos.reduce((pre,todo)=> pre + (todo.done ? 1 : 0),0)
		//总数
		const total = todos.length
		return (
			<div className="todo-footer">
				<label>
					<input type="checkbox" onChange={this.handleCheckAll} checked={doneCount === total && total !== 0 ? true : false}/>
				</label>
				<span>
					<span>已完成{doneCount}</span> / 全部{total}
				</span>
				<button onClick={this.handleClearAllDone} className="btn btn-danger">清除已完成任务</button>
			</div>
		)
	}
}