第三章：React 应用(基于 React 脚手架)

一、使用 create-react-app 创建 react 应用

1. react 脚手架

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
- 包含了所有需要的配置（语法检查、jsx 编译、devServer…）
- 下载好了所有相关的依赖
- 可以直接运行一个简单效果
react 提供了一个用于创建 react 项目的脚手架库: create-react-app
项目的整体技术架构为: react + webpack + es6 + eslint
使用脚手架开发的项目的特点: 模块化，组件化，工程化

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

# 新版安装方法!npx create-react-app myapp
cd my-app
npm start

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)

请添加图片描述

4. 功能界面的组件化编码流程（通用）

拆分组件：拆分界面，抽取组件
实现静态组件：使用组件实现静态页面效果（class -> className, style…)
实现动态组件
- 动态显示初始化数据
  - 数据类型
  - 数据名称
  - 保存在哪个组件?
- 交互(从绑定事件监听开始)

5. 代码

请添加图片描述

/* src/index.js */
//引入react核心库
import React from 'react'
//引入ReactDOM
import ReactDOM from 'react-dom'
//引入App组件
import App from './App'//渲染App到页面
ReactDOM.render(<App/>,document.getElementById('root'))

/* src/App.jsx */
//创建“外壳”组件App
import React,{Component} from 'react'
import Hello from './components/Hello'
import Welcome from './components/Welcome'//创建并暴露App组件
export default class App extends Component{render(){return (<div><Hello/><Welcome/></div>)}
}

/* src/components/Hello/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>}
}

/* src/components/Hello/index.module.css */
.title{background-color: orange;
}

/* src/components/Welcome/index.jsx */
import React,{Component} from 'react'
import './index.css'export default class Welcome extends Component{render(){return <h2 className="title">Welcome</h2>}
}

/* src/components/Welcome/index.css */
.title{background-color: skyblue;
}

二、组件的组合使用 - TodoList

功能：组件化实现此功能
- 显示所有 todo 列表
- 输入文本, 点击按钮显示到列表的首位, 并清除输入的文本

请添加图片描述

静态页面源码

<!-- index.html -->
<!doctype html>
<html lang="en">
<head><meta charset="utf-8"><title>React App</title><link rel="stylesheet" href="index.css">
</head>
<body>
<div id="root"><div class="todo-container"><div class="todo-wrap"><div class="todo-header"><input type="text" placeholder="请输入你的任务名称，按回车键确认"/></div><ul class="todo-main"><li><label><input type="checkbox"/><span>xxxxx</span></label><button class="btn btn-danger" style="display:none">删除</button></li><li><label><input type="checkbox"/><span>yyyy</span></label><button class="btn btn-danger" style="display:none">删除</button></li></ul><div class="todo-footer"><label><input type="checkbox"/></label><span><span>已完成0</span> / 全部2</span><button class="btn btn-danger">清除已完成任务</button></div></div></div>
</div></body>
</html>

/* index.css */
/*base*/
body {background: #fff;
}.btn {display: inline-block;padding: 4px 12px;margin-bottom: 0;font-size: 14px;line-height: 20px;text-align: center;vertical-align: middle;cursor: pointer;box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.05);border-radius: 4px;
}.btn-danger {color: #fff;background-color: #da4f49;border: 1px solid #bd362f;
}.btn-danger:hover {color: #fff;background-color: #bd362f;
}.btn:focus {outline: none;
}.todo-container {width: 600px;margin: 0 auto;
}
.todo-container .todo-wrap {padding: 10px;border: 1px solid #ddd;border-radius: 5px;
}/*header*/
.todo-header input {width: 560px;height: 28px;font-size: 14px;border: 1px solid #ccc;border-radius: 4px;padding: 4px 7px;
}.todo-header input:focus {outline: none;border-color: rgba(82, 168, 236, 0.8);box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(82, 168, 236, 0.6);
}/*main*/
.todo-main {margin-left: 0px;border: 1px solid #ddd;border-radius: 2px;padding: 0px;
}.todo-empty {height: 40px;line-height: 40px;border: 1px solid #ddd;border-radius: 2px;padding-left: 5px;margin-top: 10px;
}
/*item*/
li {list-style: none;height: 36px;line-height: 36px;padding: 0 5px;border-bottom: 1px solid #ddd;
}li label {float: left;cursor: pointer;
}li label li input {vertical-align: middle;margin-right: 6px;position: relative;top: -1px;
}li button {float: right;display: none;margin-top: 3px;
}li:before {content: initial;
}li:last-child {border-bottom: none;
}/*footer*/
.todo-footer {height: 40px;line-height: 40px;padding-left: 6px;margin-top: 5px;
}.todo-footer label {display: inline-block;margin-right: 20px;cursor: pointer;
}.todo-footer label input {position: relative;top: -1px;vertical-align: middle;margin-right: 5px;
}.todo-footer button {float: right;margin-top: 5px;
}

1. 静态组件

1.1 index.js

/* src/index.js */
//引入react核心库
import React from 'react'
//引入ReactDOM
import ReactDOM from 'react-dom'
//引入App组件
import App from './App'//渲染App到页面
ReactDOM.render(<App/>,document.getElementById('root'))

1.2 App

/* src/App.jsx */
//创建“外壳”组件App
import React,{Component} from 'react'
import Header from './components/Header'
import List from './components/List'
import Footer from './components/Footer'
import './App.css'//创建并暴露App组件
export default class App extends Component{render(){return (<div className="todo-container"><div className="todo-wrap"><Header/><List /><Footer /></div></div>)}
}

/* src/App.css */
/*base*/
body {background: #fff;}.btn {display: inline-block;padding: 4px 12px;margin-bottom: 0;font-size: 14px;line-height: 20px;text-align: center;vertical-align: middle;cursor: pointer;box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.05);border-radius: 4px;}.btn-danger {color: #fff;background-color: #da4f49;border: 1px solid #bd362f;}.btn-danger:hover {color: #fff;background-color: #bd362f;}.btn:focus {outline: none;}.todo-container {width: 600px;margin: 0 auto;}.todo-container .todo-wrap {padding: 10px;border: 1px solid #ddd;border-radius: 5px;}

1.3 Header

/* src/components/Header/index.jsx */
import React, { Component } from 'react'
import './index.css'export default class Header extends Component {render() {return (<div className="todo-header"><input type="text" placeholder="请输入你的任务名称，按回车键确认"/></div>)}
}

/* src/components/Header/index.css */
.todo-header input {width: 560px;height: 28px;font-size: 14px;border: 1px solid #ccc;border-radius: 4px;padding: 4px 7px;}.todo-header input:focus {outline: none;border-color: rgba(82, 168, 236, 0.8);box-shadow: inset 0 1px 1px rgba(0, 0, 0, 0.075), 0 0 8px rgba(82, 168, 236, 0.6);}

1.4 List

/* src/components/List/index.jsx */
import React, { Component } from 'react'
import Item from '../Item'
import './index.css'export default class List extends Component {render() {return (<ul className="todo-main"><Item /><Item /><Item /><Item /><Item /></ul>)}
}

/* src/components/List/index.css */
.todo-main {margin-left: 0px;border: 1px solid #ddd;border-radius: 2px;padding: 0px;}.todo-empty {height: 40px;line-height: 40px;border: 1px solid #ddd;border-radius: 2px;padding-left: 5px;margin-top: 10px;}

1.5 Item

/* src/components/Item/index.jsx */
import React, { Component } from 'react'
import './index.css'export default class Item extends Component {render() {return (<li><label><input type="checkbox"/><span>xxxxx</span></label><button className="btn btn-danger" style={{display: "none"}}>删除</button></li>)}
}

/* src/components/Item/index.css */
li {list-style: none;height: 36px;line-height: 36px;padding: 0 5px;border-bottom: 1px solid #ddd;}li label {float: left;cursor: pointer;}li label li input {vertical-align: middle;margin-right: 6px;position: relative;top: -1px;}li button {float: right;display: none;margin-top: 3px;}li:before {content: initial;}li:last-child {border-bottom: none;}

1.6 Footer

/* src/components/Footer/index.jsx */
import React, { Component } from 'react'
import './index.css'export default class Footer extends Component {render() {return (<div className="todo-footer"><label><input type="checkbox"/></label><span><span>已完成0</span> / 全部2</span><button className="btn btn-danger">清除已完成任务</button></div>)}
}

/* src/components/Footer/index.css */
.todo-footer {height: 40px;line-height: 40px;padding-left: 6px;margin-top: 5px;}.todo-footer label {display: inline-block;margin-right: 20px;cursor: pointer;}.todo-footer label input {position: relative;top: -1px;vertical-align: middle;margin-right: 5px;}.todo-footer button {float: right;margin-top: 5px;}

2. 动态初始化列表

2.1 App

/* src/App.jsx */
//创建“外壳”组件App
import React,{Component} from 'react'
import Header from './components/Header'
import List from './components/List'
import Footer from './components/Footer'
import './App.css'//创建并暴露App组件
export default class App extends Component{//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}]}render(){const {todos} = this.statereturn (<div className="todo-container"><div className="todo-wrap"><Header/><List todos={todos}/><Footer /></div></div>)}
}

2.2 List

/* src/components/List/index.jsx */
import React, { Component } from 'react'
import Item from '../Item'
import './index.css'export default class List extends Component {render() {const {todos} = this.propsreturn (<ul className="todo-main">{todos.map(todo=> {return <Item key={todo.id} {...todo}/>})}</ul>)}
}

2.3 Item

/* src/components/Item/index.jsx */
import React, { Component } from 'react'
import './index.css'export default class Item extends Component {render() {const {name,done} = this.propsreturn (<li><label><input type="checkbox" defaultChecked={done}/><span>{name}</span></label><button className="btn btn-danger" style={{display: "none"}}>删除</button></li>)}
}