Simple List

List.js

function List() {
  this.head = this.tail = null
}

List.prototype.add =  function add(node) {
  if (this.head) {
    node.next = this.head;
    this.head.prev = node;
  }
  this.head = node;
  this.tail = this.tail || node;
};

List.prototype.remove = function remove(node) {
  node.prev ? node.prev.next = node.next : this.head = node.next;
  node.next ? node.next.prev = node.prev : this.tail = node.prev;
};

List.prototype.moveToFront = function(node) {
  this.remove(node);
  this.add(node);
};

List.prototype.print = function() {
  var temp = this.head;
  while(temp) {
    console.log(temp.val)
    temp = temp.next;
  };
};

function Node(key, val) {
  this.key = key;
  this.val = val;
  this.prev = this.next = null;
}