Taking a node in rootA and finding a clone node in other tree
It looks like the solution solves the wrong problem: the rootA is completely ignored, as well as the fact that the trees are actually DOM. In a DOM structure it is safe to assume that the node has an access to its parent and siblings. So, given a node in rootA tree, you may trace its path to the root, and then descend the same path down from rootB. Since they are clones, such descend will get you to the node in question. I don't see the need (other than unit test purposes) to compare nodes.