Simple Javascript Linked List

LinkedList.js

var LinkedList = function() {
    var head, tail;

    var Node = function(dat) {

        var _node = this,
            _next = null,
            _previous = null,
            _data = dat;

        this.gotoHead = function() {
            return head;
        };
        this.gotoTail = function() {
            return tail;
        };
        this.setData = function(data) {
            _data = data;
        };
        this.getData = function() {
            return _data;
        };
        this.getPrev = function() {
            return _previous;
        };
        this.getNext = function() {
            return _next;
        };
        this.setNext = function(to) {
            _next = to;
        };
        this.setPrev = function(prev) {
            _previous = prev;
        };
    };

    head = new Node();
    tail = new Node();
    head.setPrev(tail);
    tail.setNext(head);

    this.add = function(data) {
        var n = head.getNext();
        var p = head; //previous
        while (n !== null) {
            p = n;
            n = n.getNext();
        }
        n = new Node(data);
        p.setNext(n);
        n.setPrev(p);
    };

    //get's the 0 based i'th node, returns null otherwise.
    this.get = function(i) {
        var count,
            p,
            n = head.getNext();

        while (n !== null) {
            if (count == i) { //i wouldnt mind a string.
                return n;
            }
            count++;
            n = n.getNext();
        }

        return null;
    };

    this.iterate = function(iter) {
        var n = head.getNext();
        while (n !== null) {
            iter(n);
            n = n.getNext();
        }
    };
    //Applies the function iter to every node in the linked list's data attribute.
    this.iterateData = function(iter) {
        var n = head.getNext();
        while (n !== null) {
            iter(n.getData());
            n = n.getNext();
        }
    };
};


//Sample Usage
var LLIST = new LinkedList();
LLIST.add('sup');
LLIST.add('yo');
LLIST.add({
    message: 'cool'
});
LLIST.add(6);

//
LLIST.iterate(
    function(node) {
        console.log(node.getData());
    }
);