本节知识点

(1) 无状态组件和有状态组件的区别
(2) 无状态组件的使用

(一)无状态组件和有状态组件的区别

(1)传统组件都会有钩子函数，生命周期函数等等比如

import React, { Component } from 'react'
import store from './store/index'
import * as actions from './store/actions'
import Listdo from './Listdo'
class App extends Component {
  constructor(props) {
    super(props)
    this.state = store.getState()
    store.subscribe(this.changeStore.bind(this))
  }

  render() {
    return (
      <Listdo
        message={this.state.message}
        list={this.state.list}
        changeValue={this.changeValue.bind(this)}
        changeStore={this.changeStore.bind(this)}
        changelist={this.changelist.bind(this)}
        deleteone={this.deleteone.bind(this)}
      />
    )
  }
  componentDidMount() {
    store.dispatch(actions.get_data())
  }
  changeValue(e) {
    let value = e.target.value
    store.dispatch(actions.change_value(value))
  }
  changelist() {
    store.dispatch(actions.change_list())
  }
  changeStore() {
    this.setState(store.getState())
  }
  deleteone(index) {
    store.dispatch(actions.delete_one(index))
  }
}

export default App

(2) 而无状态组件没有这些，因为里面没有逻辑没有方法只有UI展示,所以他不用继承那些个类,只是暴露个方法即可

方法传递都需要通过props

import React, { Fragment } from 'react'
const Todolist = props => {
  return (
    <Fragment>
      <input type="text" value={props.message} onChange={props.changeValue} />
      <button onClick={props.changelist}>提交</button>
      <ul>
        {props.list.map((item, index) => {
          return (
            <li
              key={index}
              onClick={() => {
                props.deleteone(index)
              }}
            >
              <span>第{index}个+++</span>
              <span>{item}</span>
            </li>
          )
        })}
      </ul>
    </Fragment>
  )
}
export default Todolist