doesRequireClone() — react Function Reference

Source Code

packages/react-reconciler/src/ReactFiberCompleteWork.js lines 216–240

function doesRequireClone(current: null | Fiber, completedWork: Fiber) {
  const didBailout = current !== null && current.child === completedWork.child;
  if (didBailout) {
    return false;
  }

  if ((completedWork.flags & ChildDeletion) !== NoFlags) {
    return true;
  }

  // TODO: If we move the `doesRequireClone` call after `bubbleProperties`
  // then we only have to check the `completedWork.subtreeFlags`.
  let child = completedWork.child;
  while (child !== null) {
    const checkedFlags = Cloned | Visibility | Placement | ChildDeletion;
    if (
      (child.flags & checkedFlags) !== NoFlags ||
      (child.subtreeFlags & checkedFlags) !== NoFlags
    ) {
      return true;
    }
    child = child.sibling;
  }
  return false;
}