React - useCallback

作用：在组件多次重新渲染时缓存函数

import { memo, useCallback, useState } from 'react'

const MemoInput = memo(function Input({ onChange }) {
  console.log('执行子组件重新渲染')
  return <input type="text" onChange={(e) => onChange(e.target.value)} />
})

function App() {
  const changeHandle = useCallback((val) => {
    console.log(val)
  }, [])

  const [count, setCount] = useState(0)
  return (
    <div className="App">
      <MemoInput onChange={changeHandle} />
      <button onClick={() => setCount(count + 1)}>{count}</button>
    </div>
  )
}

export default App