IdenticalDOMNode.js

//Given 2 identical DOM trees (but not equal) and one element of the first DOM tree, 
//how would you find this element in the second DOM tree
//Questions to ask:
//1. Input: input node is inside DOM tree? Or need to check if it exists?
//2. Output node needs to be identical? Same tag?
//3. Are comments, texts considered as child nodes? - Yes, need to use childNodes, No, use children.
var sameLevelNodeIdenticalTrees = {
  getIndexOf: function(nodeList, node){
    return Array.prototype.indexOf.call(nodeList, node);
  },
  traverseByPath: function(path, treeRoot){
    var foundNode = treeRoot;
    
    for (var i = path.length - 1; i >= 0; i--){
      var position = path[i];
      
      if (foundNode && foundNode.children){
        foundNode = foundNode.children[position];
      }
      else{
        foundNode = undefined;
        break;
      }
    }
    
    return foundNode;
  },
  findPath: function(node, treeRoot){
    var path = [];
    
    if (node){
      while (node && node !== treeRoot){
        var parent = node.parentNode;
        if (parent){
          var index = this.getIndexOf(parent.children, node);
          
          if (index !== -1){
            path.push(index);
          }
        }
        else{
          if (treeRoot !== node){
            path.length = 0;
            break;
          }
        }
        
        node = parent;
      }
    }
    
    return path;
  },
  find: function(rootTreeA, nodeA, rootTreeB){
    if (!rootTreeA || !nodeA || !rootTreeB) return undefined;
    if (rootTreeA === nodeA) return rootTreeB;
    
    var path = this.findPath(nodeA, rootTreeA), nodeB = undefined;
    
    if (path && path.length > 0){
      nodeB = this.traverseByPath(path, rootTreeB);
    }
    else{
      throw Error('Node A is not in Tree A');
    }
    
    return nodeB;
  }
};