Try this way to check the Browser Compability,
if(window.XMLHttpRequest)
{
ajaxRequest = new XMLHttpRequest();
}
else
{
ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
}
ajaxRequest.onreadystatechange=function()
{
if(ajaxRequest.readyState == 4)
{
document.getElementById("YourOutPutID").innerHTML = ajaxRequest.responseText;
}
}
ajaxRequest.open("GET", "index.php?vote="+vote,true);
ajaxRequest.send();
}