A Java Script Linked List Class!

linked_list_2.js

function LinkedList() {
  this._length = 0;
  this._head = null;
}

LinkedList.prototype = {

  add: function (data){
    var node = {
      data: data,
      next: null
    },
    current;
    if (this._head === null){
      this._head = node;
    } else {
      current = this._head;
      while(current.next){
        current = current.next;
      }
      current.next = node;
    }
    this._length++;
  },

  push: function (data){
    this._head = {
      data: data,
      next: this._head
    };
    this._length++;
  },

  pop: function(pos){
    var current = this._head;
    for (var i = 0; i < pos; i++){
      current = current.next;
    }
    var gotchya = current.data;
    if (current.next){
      current.data = current.next.data;
      current.next = current.next.next;
    } else {
      this._head = null;
    }
    this._length--;
    return gotchya;
  },

  isElement: function(value2){
    var current = this._head;
    while (current != null){
      if (current.data == value2)
        return true;
      current = current.next;
    }
    return false;
  },

  isEmpty: function(){
    if (this._head == null)
      return true;
    else
      return false;
  }

};

{ data:1, next{ data:2, next{ data:3, next:null }}}