import React from 'react'
import Child from './Child'

const dataList = [
 { id: '001', value: '张三' },
 { id: '002', value: '李四' }
]

const Parent = props => {
 return (
  <ul>
   <Child dataList={dataList}></Child>
  </ul>
 )
}

export default Parent

import React from 'react'

const Child = props => {
 return (
  <React.Fragment>
   {
    props.dataList.map(item => <li key={item.id}>{item.value}</li>)
   }
  </React.Fragment>
 )
}

export default Child

import React, { useState } from 'react'
import Child from './Child'

const Parent = props => {
 const [count, setCount] = useState(0)

 return (
  <Child count={count} setCount={setCount}></Child>
 )
}

export default Parent

import React from 'react'

const Child = props => {
 return (
  <React.Fragment>
   <button onClick={() => {props.setCount(props.count-1)}}>-</button>
   <span>{props.count}</span>
   <button onClick={() => {props.setCount(props.count+1)}}>+</button>
  </React.Fragment>
 )
}

export default Child

import React, { useState } from 'react'
import Child from './Child'

export const MyContext = React.createContext('hello')

const Parent = props => {
 return (
  <MyContext.Provider value="world">
   <Child />
  </MyContext.Provider>
 )
}

export default Parent

import React from 'react'
import Son from './Son'

const Child = props => {
 return (
  <Son />
 )
}

export default Child

import React from 'react'
import { MyContext } from './Parent'

export default class Son extends React.Component {
 render() {
  return (
   <MyContext.Consumer>
    {
     context => <div>{context}</div>
    }
   </MyContext.Consumer>
  )
 }
}