10.useImperativeHandle应用案例及源码实现

应用案例

const MyInput = React.forwardRef(function MyInput(props, ref) {
  const inputRef = useRef(null);

  useImperativeHandle(ref, () => {
    return {
      focus() {
        inputRef.current.focus();
      },
      scrollIntoView() {
        inputRef.current.scrollIntoView();
      },
    };
  }, []);

  return <input {...props} ref={inputRef} />;
});

export default function Form() {
  const ref = useRef(null);

  function handleClick() {
    ref.current.focus();
    // This won't work because the DOM node isn't exposed:
    // ref.current.style.opacity = 0.5;
  }

  return (
    <form>
      <MyInput label="Enter your name:" ref={ref} />
      <button type="button" onClick={handleClick}>
        Edit
      </button>
    </form>
  );
}
ReactDOM.render(<Form />, document.getElementById('root'));

源码实现

export function useImperativeHandle(ref, dataFactory) {
  ref.current = dataFactory();
}