window.setInterval("getxhr()",6000);

function getxhr(){
var xhr = null;
if (window.XMLHttpRequest){
xhr = new XMLHttpRequest();
} 
else {
if (window.ActiveXObject){
xhr = new ActiveXObject("Microsoft.XMLHTTP");
} 
}
xhr.onreadystatechange = function(){ 
if(xhr.readyState == 4 && xhr.status == 200){
	document.getElementById("DivElement").innerHTML = xhr.responseText ;
	document.getElementById("charge").style.visibility="hidden";
}	
}
var i = 11;
b = Math.floor(i * Math.random());
xhr.open("post", "script.php", true); 
document.getElementById("charge").style.visibility="visible";
xhr.send(null); 
}