Create a linked list, with method add and contain

LinkedList.js

function Node (next) {
	this.next = next;
}

function LinkedList () {

	this.add = function (node) {
		if (!this.head) {
			this.head = node;
			this.tail = node;
		} else {
			this.tail.next = node;
			this.tail = node;
		}

	};

	this.contain = function (node) {
		var cursor = this.head;
		while (cursor) {
			if (cursor === node) {
				return true;
			}
			cursor = cursor.next;
		}
		return false;
	};
}