LinkedList created by ZaynahGiti - https://repl.it/EPbx/1

LinkedList.js

function LinkedList() {
 this.head = null;
 this.tail = null;
}
 
function Node(value, next, prev) {
 this.value = value;
 this.next = next;
 this.prev = prev;
}
 
LinkedList.prototype.addToHead = function(value) {
 var newNode = new Node(value, this.head, null);
 if (this.head) this.head.prev = newNode;
 else this.tail = newNode;
 this.head = newNode;
};
 
LinkedList.prototype.addToTail = function(value) {
 var newNode = new Node(value, null, this.tail);
 if (this.tail) this.tail.next = newNode;
 else this.head = newNode;
 this.tail = newNode;
};
 
LinkedList.prototype.removeHead = function() {
 if (!this.head) return null;
 var val = this.head.value;
 this.head = this.head.next;
 if (this.head) this.head.prev = null;
 else this.tail = null;
 return val;
};
 
LinkedList.prototype.removeTail = function() {
 if (!this.tail) return null;
 var val = this.tail.value;
 this.tail = this.tail.prev;
 if (this.tail) this.tail.next = null;
 else this.head = null;
 return val;
};
 
LinkedList.prototype.search = function(searchValue) {
 var currentNode = this.head;
 while (currentNode) {
 if (currentNode.value === searchValue) return currentNode.value;
 currentNode = currentNode.next;
 } 
 return null;
};