function LinkedList(){

this.head = null;

}

LinkedList.prototype.push = function(val){

var node = {

value: val,

next: null

}

if(!this.head){

this.head = node;

}

else{

current = this.head;

while(current.next){

current = current.next;

}

current.next = node;

}

}

var sll = new LinkedList();

//push node

sll.push(2);

sll.push(3);

sll.push(4);

//check values by traversing LinkedList

console.log(sll.head); //Object {data: 2, next: Object}

console.log(sll.head.next); //Object {data: 4, next: null}

console.log(sll.head.next.next); //Object {data: 4, next: null}