detachAlternateSiblings() — react Function Reference

Source Code

packages/react-reconciler/src/ReactFiberCommitWork.js lines 4771–4797

function detachAlternateSiblings(parentFiber: Fiber) {
  // A fiber was deleted from this parent fiber, but it's still part of the
  // previous (alternate) parent fiber's list of children. Because children
  // are a linked list, an earlier sibling that's still alive will be
  // connected to the deleted fiber via its `alternate`:
  //
  //   live fiber --alternate--> previous live fiber --sibling--> deleted
  //   fiber
  //
  // We can't disconnect `alternate` on nodes that haven't been deleted yet,
  // but we can disconnect the `sibling` and `child` pointers.

  const previousFiber = parentFiber.alternate;
  if (previousFiber !== null) {
    let detachedChild = previousFiber.child;
    if (detachedChild !== null) {
      previousFiber.child = null;
      do {
        // $FlowFixMe[incompatible-use] found when upgrading Flow
        const detachedSibling = detachedChild.sibling;
        // $FlowFixMe[incompatible-use] found when upgrading Flow
        detachedChild.sibling = null;
        detachedChild = detachedSibling;
      } while (detachedChild !== null);
    }
  }
}