react函数组件，父组件调用子组件的方法

1. 父组件

  if(!childRef) childRef = React.useRef()
  
  const setRef = (ref) => {
    childRef = ref
  }
  
  const getChildInfo = () => {
      childRef.current.method1();
  }
  
<Child ref={setRef}/>

2. 子组件

import React, {forwardRef, useImperativeHandle} from 'react';
const Child = forwardRef(props, ref) => {
    useImperativeHandle(ref,()=>({method1})) //对外暴露的方法

    return ...
}