Vote Restriction Coding Error by Programmer - cookies

Question

I am not able to properly launch my site at http://www.enbloc.sg
This is because my programmer is not able to figure out a problem. Any help would be much appreciated.
Visitors vote by clicking on one colour on the traffic light. They are supposed to only have one vote.
The site first checks for cookies and then ip address of voter. If the 2 are identical to a previous visitor, then voting is not allowed. If only one of the 2 are repeated, then voting is permitted.
The idea of having a double restriction is to allow different voters behind a fixed IP to vote. E.g. the employees of a company would not be able to vote since they are likely to be accessing the site via a fixed IP address.
However, currently, visitors are able to click on ALL 3 colours to register 3 votes on their first visit to the site. My coder is not able to resolve this issue and has abandoned me.
I would be most grateful if someone can help. I believe the relevant codes are appended below.
Apologies if my posting is wrongly formatted.
Thanks very much,
Lin En
Extracted from http://www.enbloc.sg/js/functions.js
//update dashboard when vote by user
function vote_update(ip_address, issue_num, vote_status){
var vote_cookie = document.getElementById('vote_cookie').value;
if(vote_cookie != '')
{
if(document.getElementById('thanks').style.display == "none")
{
$("#multi_error").fadeIn("slow");
}
else
{
document.getElementById("thanks").style.display = "none";
$("#multi_error").fadeIn("slow");
}
}
else
{
if(ip_address != ' ' && issue_num != ' ')
{
http.open("POST", "update_vote.php"); // true
http.onreadystatechange = update_vote;
http.setRequestHeader("Content-Type", "application/x-www-form- urlencoded;charset=UTF-8");
http.send("ip="+ ip_address +"&issue_num="+ issue_num + "&vote_status=" + vote_status);
}
else
{
alert("Occur Error for IP or ISSUE!");
}
}
}
// ajax response function
function update_vote(){
if (http.readyState == 4)
{
if (http.status == 200)
{
var xmlDoc = http.responseXML;
var listElements = xmlDoc.getElementsByTagName("list");
var result = listElements[0].getElementsByTagName("total") [0].childNodes[0].nodeValue;
if (result == 1)
{
var issue_num = listElements[0].getElementsByTagName("issue")[0].childNodes[0].nodeValue;
var vote = listElements[0].getElementsByTagName("vote") [0].childNodes[0].nodeValue;
$("#thanks").fadeIn("slow");
load(issue_num, vote);
}
else if (result == 'Multi')
{
if(document.getElementById('thanks').style.display == "none")
{
$("#multi_error").fadeIn("slow");
}
else
{
document.getElementById("thanks").style.display = "none";
$("#multi_error").fadeIn("slow");
}
}
else
{
alert("error");
}
}
}
}

Answer 1

These changes will help:
var already_voted = false;
function vote_update(ip_address, issue_num, vote_status)
{
if(alread_voted) return;
already_voted = true;
// rest of the code
}
This will make sure that only one vote can be cast during a single visit. The cookies take care of the rest and are already working fine.