React useRef

useRef

• 应用场景：绑在DOM上，绑在组件上，保存临时变量永远不丢失

1. 举个栗子

import React, { useState,useRef } from 'react'

export default function App() {
  const [count, setCount] = useState(6)
  var mycount = useRef(0); // 临时变量 mycount.current
 
  return (
    <div>
      <button onClick={
        ()=> {
          setCount(count + 1)
          // mycount++;
          mycount.current++ 
        }
      }>add</button>
      { count }-{ mycount.current }
    </div>
  )
}