Function Child

packages/react-reconciler/src/__tests__/StrictEffectsMode-test.js:551–562

()

    const log = [];
    let _setShowChild;
    function Child() {
      React.useEffect(() => {
        log.push('Child useEffect mount');
        return () => log.push('Child useEffect unmount');
      });
      React.useLayoutEffect(() => {
        log.push('Child useLayoutEffect mount');
        return () => log.push('Child useLayoutEffect unmount');
      });

      return null;
    }

    function App() {
      const [showChild, setShowChild] = React.useState(false);