Function isFiberMountedImpl

code/controlled-uncontrolled/public/app.js:4439–4466

(fiber)

var UNMOUNTED = 3;

function isFiberMountedImpl(fiber) {
  var node = fiber;
  if (!fiber.alternate) {
    // If there is no alternate, this might be a new tree that isn't inserted
    // yet. If it is, then it will have a pending insertion effect on it.
    if ((node.effectTag & Placement) !== NoEffect) {
      return MOUNTING;
    }
    while (node['return']) {
      node = node['return'];
      if ((node.effectTag & Placement) !== NoEffect) {
        return MOUNTING;
      }
    }
  } else {
    while (node['return']) {
      node = node['return'];
    }
  }
  if (node.tag === HostRoot) {
    // TODO: Check if this was a nested HostRoot when used with
    // renderContainerIntoSubtree.
    return MOUNTED;
  }
  // If we didn't hit the root, that means that we're in an disconnected tree
  // that has been unmounted.
  return UNMOUNTED;
}

function isFiberMounted(fiber) {
  return isFiberMountedImpl(fiber) === MOUNTED;