ajax

function ajax_post(fn){
    var hr = new XMLHttpRequest();
    var url = "process2.php";
    var fn;
    var vars = "num="+fn;
    hr.open("POST", url, true); //tru
    hr.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    hr.onreadystatechange = function() {
	    if(hr.status == 4&&hr.status == 200) {
		    var return_data = hr.responseText;
			document.getElementById("status").innerHTML = return_data;
			ajax_post(return_data); //HERE I TRY TO CALL ITSELF
	    }
    }
    hr.send(vars);
    document.getElementById("status").innerHTML = "processing...";
}