Tree [JavaScript]

tree.js

function Node(data) {
  this.data = data;
  this.parent = null;
  this.children = [];
}

function Tree(data) {
  var node = new Node(data);
  this._root = node;
}

Tree.prototype.traverseDF = function(callback) {
  (function recurse(currentNode) {
    for (var i = 0; i < currentNode.children.length; i++) {
      recurse(currentNode.children[i]);
    }
    callback(currentNode);
  })(this._root);
}

Tree.prototype.traverseBF = function(callback) {
  var queue = [];
  queue.push(this._root);
  var currentNode = queue.shift();

  while (currentNode) {
    for (var i = 0; i < currentNode.children.length; i++) {
      queue.push(currentNode.children[i]);
    }

    callback(currentNode);
    currentNode = queue.shift();
  }
}

Tree.prototype.contains = function(callback, traversal) {
  traversal.call(this, callback);
};

Tree.prototype.add = function(data, toData, traversal) {
  var child = new Node(data);
  var parent = null;
  var callback = function(node) {
    if (node.data === toData) {
      parent = node;
    }
  };

  this.contains(callback, traversal);

  if (parent) {
    parent.children.push(child);
    child.parent = parent;
  } else {
    throw new Error('Cannot add node to a non-existent parent');
  }
};

Tree.prototype.remove = function(data, traversal) {
  var nodeToRemove = null;
  
  var callback = function(node) {
    if (node.data === data) {
      nodeToRemove = node;
    }
  };
  
  this.contains(callback, traversal);
  
  if (nodeToRemove) {
    var parent = nodeToRemove.parent;
    var index;

    for (var i = 0; i < parent.children.length; i++) {
      if (parent.children[i].data === data) {
        index = i;
      }
    }

    parent.children.splice(index, 1);
    nodeToRemove.parent = null;
  } else {
    throw new Error('Cannot remove a non-existent node');
  }

  return nodeToRemove;
};

var tree = new Tree('one');

tree.add('two', 'one', tree.traverseBF);
tree.add('three', 'one', tree.traverseBF);

tree.add('four', 'two', tree.traverseBF);
tree.add('five', 'two', tree.traverseBF);

tree.add('six', 'three', tree.traverseBF);
tree.add('seven', 'three', tree.traverseBF);

tree.remove('three', tree.traverseBF);

tree.traverseBF(function(node) {
  console.log(node.data);
});