Dynamic amount of '.parent'

Question

I have 2 object. In different depths of MovieClip. I would like to know if object A parent is same with object B parent. I wanted to dynamically add '.parent' to object A/B till it both reaches the same level (having the same parent object). How can I do that?

My idea was to have something like

objectA = objectA + ".parent"

and make it loop till it reaches the target. But this is not the correct way to add in more layers of '.parent'. Anyone know how it should be coded?

Answer 1

var mc:MovieClip;
while (mc.parent != null && mc.parent != targetParent)
{
    mc = mc.parent;
}

Answer 2

You can use contains method

public function contains(child:DisplayObject):Boolean
Determines whether the specified display object is a child of the DisplayObjectContainer instance or the instance itself. The search includes the entire display list including this DisplayObjectContainer instance, grandchildren, great-grandchildren, and so on.

function haveCommonParent(a:DisplayObject, b:DisplayObject):Boolean
{
  for(var p:DisplayObjectContainer = a.parent; p != null; p = p.parent)
  {
      if(p.contains(b))
          return true;
  }
  return false;
}

Might be slow for huge display lists.

Update: get the common parent, if any. This will return a Stage object if both are on stage.

function getCommonParent(a:DisplayObject, b:DisplayObject):DisplayObjectContainer
{
  for(var p:DisplayObjectContainer = a.parent; p != null; p = p.parent)
  {
      if(p.contains(b))
          return p;
  }
  return null;
}