text: import React, { useRef, forwardRef } from 'react'
  
  const SQInput = forwardRef((props, ref) => {
    return <input ref={ref} type="text" />
  })
  
  export default function ForwardRefDemo() {
    const inputRef = useRef()
  
    return (
      <div>
        <SQInput ref={inputRef} />
        <button onClick={e => inputRef.current.focus()}>聚焦</button>
      </div>
    )
  }
  