HackerRank Day 15 of 30 days of code challenge

LinkedList.js

//https://www.hackerrank.com/challenges/30-linked-list/problem?isFullScreen=true


process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});
function readLine() {
    return input_stdin_array[input_currentline++];
}
function Node(data){
    this.data=data;
    this.next=null;
}
function Solution(){

	this.insert=function(head,data){
          //complete this method
          if (head == undefined) {
              head = new Node(data);
          } else {
             if (head.next == undefined){
                 head.next = new Node(data);
             }
             else {
                 this.insert(head.next, data);
             }
          }
          return head
    };

	this.display=function(head){