This algorithm displays how you can locate the same node in another identical DOM tree.

FindIdenticalNode.js

// Helper function to provide Array's indexOf method to DOM elements
function indexOf(arr, target) {
  return Array.prototype.indexOf.call(arr, target);
}

// Get the path of the target node from Root A
function getPath(root, target) {
  let current = target;
  let path = [];
  while(current !== root) {
    path.unshift(indexOf(current.parentNode.childNodes, current));
    current = current.parentNode;
  }
  return path;
}

// Given a node path, map it to the node
function locateNodeFromPath(root, path) {
 let target = root;
 for(let i=0; i < path.length; i++) {
   target = target.childNodes[path[i]];
 }
  return target;
}

// Given two identical DOM trees and a target node, find the corresponding node
function getIdenticalNode(rootA, rootB, target){
  return locateNodeFromPath(rootB, getPath(rootA, target));
}