function ajax() {
function createRequestObject(){
	var request_o; 
	var browser = navigator.appName; 
	if(browser == "Microsoft Internet Explorer"){
		request_o = new ActiveXObject("Microsoft.XMLHTTP");
	}else{
		request_o = new XMLHttpRequest();
	}
	return request_o;
}

var http = createRequestObject(); 

function getResult(){
	http.open('get', 'comment.php');
	http.onreadystatechange = handleResult; 
	http.send(null);
}

function handleResult(){
	if(http.readyState == 4){ 
		var response = http.responseText;
		document.getElementById('comm').innerHTML = response;
	}
}
}