构建React TodoList应用：管理你的任务清单

npx create-react-app todo-list-app
cd todo-list-app

// Header组件
import React, { Component } from 'react'
import style from './Header.module.css'

export default class Header extends Component {
  state = { value: '' }

  handleChange = (e) => {
    this.setState({ value: e.target.value })
  }

  handleEnter = (e) => {
    if (e.key === 'Enter') {
      this.props.handleAdd(this.state.value)
      this.setState({ value: '' })
    }
  }

  render() {
    const { value } = this.state

    return (
      <div className={style.header}>
        <input
          placeholder="What needs to be done?"
          className={style.input}
          value={value}
          type="text"
          onChange={this.handleChange}
          onKeyDown={this.handleEnter}
        />
      </div>
    )
  }
}

// TodoList组件
import React, { Component } from 'react'
import Item from '../TodoItem'
import style from './TodoList.module.css'

export default class TodoList extends Component {
  handleChange = (item) => {
    const { data } = this.props;
    const newData = data.map(it => it.id === item.id ? item : it);
    this.props.handleChange(newData);
  }

  render() {
    const { data } = this.props;

    return (
      <div className={style.list}>
        {
          data.map(it => <Item {...it} key={it.id} handleChange={this.handleChange} />)
        }
      </div>
    )
  }
}

// Footer组件
import React, { Component } from 'react'
import style from './Footer.module.css'

export default class Footer extends Component {
  state = {
    checked: false
  }

  onClear = () => {
    const { data } = this.props;
    const newData = data.filter(it => !it.checked);
    this.props.handleChange(newData);
    this.setState({ checked: false });
  }

  handleCheck = (e) => {
    const checked = e.target.checked;
    const { data } = this.props;
    let newData = data.map(it => ({ ...it, checked }));
    this.props.handleChange(newData);
    this.setState({ checked });
  }

  render() {
    const { checked } = this.state;
    const { data } = this.props;
    const completedCount = data.filter(it => it.checked).length;

    return (
      <div className={style.footer}>
        <input type="checkbox" checked={checked} onChange={this.handleCheck} />
        <span className={style.selected}>已完成{completedCount}/全部{data.length}</span>
        <button className={style.button} onClick={this.onClear}>清除已完成任务</button>
      </div>
    )
  }
}

// App.js
import React, { Component } from 'react'
import Header from './components/Header'
import TodoList from './components/TodoList'
import Footer from './components/Footer'
import style from './App.module.css'

const initialTodos = [
  { id: 'bv2LBfNfFl', value: 'React', checked: false },
  { id: 'tBrIBgKu4l', value: '你好', checked: true },
  { id: '9FXIFbKJ69', value: 'Vue', checked: false },
];

export default class TodoListApp extends Component

 {
  state = {
    data: initialTodos,
  }

  handleAdd = (value) => {
    const { data } = this.state
    this.setState({ data: [{ id: generateRandomString(), value, checked: false }, ...data] })
  }

  handleChange = (data) => {
    this.setState({ data });
  }

  render() {
    const { data } = this.state;

    return (
      <div className={style.todoList}>
        <Header handleAdd={this.handleAdd} />
        <TodoList data={data} handleChange={this.handleChange} />
        <Footer data={data} handleChange={this.handleChange} />
      </div>
    )
  }
}

npm start