A preliminary implementation of a basic LinkedList

LinkedList.js

/**
 * @author onteria
 * @description A library of functions to handle linked lists
 * @name LinkedList
 */

// Expose our objects to APIs that use require()
exports.LinkedList = LinkedList;
exports.ListNode = ListNode;

/**
 * @description Call a function on each of the list nodes
 * @param {function} callback The function to call on each node in the form function(current_node) { }
 */
function EachNode(callback) {
  var current_node = this.head;
  for(var i = 0; i < this.length; i++) {
    callback(current_node.value);
    if(current_node.nextNode != undefined) {
      current_node = current_node.nextNode;
    }
  }
}

/**
 * @description Prepend a node to the head of a linked list
 * @param {object} object the object to add to the start of the list
 */
function PrependNode(object) {
  if (this.head == undefined) {
    this.head = new ListNode(object);
  }
  else {
    var tmp_node = new ListNode(object);

    // Keep a placeholder of the current head value
    var current_head = this.head;

    // Point it's previous node to the new node
    current_head.prevNode = tmp_node;

    // and point the new node at the previous head node
    tmp_node.nextNode = current_head;

    // Finally make the new node the head node
    this.head = tmp_node;
  }

  this.length++;
}

/**
 * @description Append a node to the end of a linked list
 * @param {object} object the object to add to the end of the list
 */
function AppendNode(object) {
  var tmp_node = new ListNode(object);

  if (this.head == undefined) {
    this.head = tmp_node;
  }
  // Only the head node exists
  else if (this.length == 1) {
    tmp_node.prevNode = this.head;
    this.head.nextNode = tmp_node;
  }
  else {

    // We loop through the nodes until we get to the end
    // The length property of our list lets us know when
    // to stop.
    var current_node = this.head;
    for (var i = 1; i < this.length; i++) {
      current_node = current_node.nextNode;
    }

    // Now, insert the temporary node at the end
    tmp_node.prevNode = current_node;
    current_node.nextNode = tmp_node;
  }

  this.length++;
}

/**
 * @field
 * @description Constructor to create a linked list
 * @param {array} object_array An array of objects to populate the list
 * @param {bool} prepend If true, prepend the objects, if false, append the objects (default: true)
 * @return {object} The constructed LinkedList object
 */
function LinkedList(object_array, prepend) {
  prepend = (prepend == undefined) ? true : prepend;

  this.head = undefined;
  this.length = 0;
  this.PrependNode = PrependNode;
  this.AppendNode = AppendNode;
  this.EachNode = EachNode;

  if (object_array.constructor == Array && object_array.length > 0) {
    object_array.forEach(
        function(object) {
          if (prepend) {
            this.PrependNode(object);
          }
          else {
            this.AppendNode(object);
          }
        }, this
    );
  }
}

/**
 * @field
 * @description Constructor to create a linked list node
 * @param {ListNode} previousNode An object to set as the previous node
 * @param {ListNode} nextNode An object to set as the next node
 * @return {object} The constructed LinkedList object
 */
function ListNode(value, previousNode, nextNode) {
  this.value = value;
  this.prevNode = previousNode;
  this.nextNode = nextNode;
}