30秒学会 React 片段 – React useHover hook

Handles the event of hovering over the wrapped component.

• Use the useState() hook to create a variable that holds the hovering state.
• Use the useCallback() hook to memoize two handler functions that update the state.
• Use the useCallback() hook to create a callback ref and create or update the listeners for the 'mouseover' and 'mouseout' events.
• Use the useRef() hook to keep track of the last node passed to callbackRef to be able to remove its listeners.

代码实现

const useHover = () => {
  const [isHovering, setIsHovering] = React.useState(false);

  const handleMouseOver = React.useCallback(() => setIsHovering(true), []);
  const handleMouseOut = React.useCallback(() => setIsHovering(false), []);

  const nodeRef = React.useRef();

  const callbackRef = React.useCallback(
    node => {
      if (nodeRef.current) {
        nodeRef.current.removeEventListener('mouseover', handleMouseOver);
        nodeRef.current.removeEventListener('mouseout', handleMouseOut);
      }

      nodeRef.current = node;

      if (nodeRef.current) {
        nodeRef.current.addEventListener('mouseover', handleMouseOver);
        nodeRef.current.addEventListener('mouseout', handleMouseOut);
      }
    },
    [handleMouseOver, handleMouseOut]
  );

  return [callbackRef, isHovering];
};

使用样例

const MyApp = () => {
  const [hoverRef, isHovering] = useHover();

  return <div ref={hoverRef}>{isHovering ? 'Hovering' : 'Not hovering'}</div>;
};

ReactDOM.createRoot(document.getElementById('root')).render(
  <MyApp />
);

翻译自：https://www.30secondsofcode.org/react/s/use-hover