var xmlhttp;

function output(){}

function counter(id) {
	if(window.XMLHttpRequest){ // code for Mozilla, Safari, etc 
		xmlhttp=new XMLHttpRequest();
		xmlhttp.onreadystatechange=output;
		xmlhttp.open("GET", "counter.php?id=" + id, true); // leave true for Gecko
		xmlhttp.send(null);
	} 
	else if (window.ActiveXObject) { //IE 
		xmlhttp=new ActiveXObject('Microsoft.XMLHTTP'); 
		if(xmlhttp) {
			xmlhttp.onreadystatechange=output;
			xmlhttp.open('GET', "counter.php?id=" + id, false);
			xmlhttp.send();
		}
	}
	else {
		xmlhttp=false;
	}
}