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

var http = createRequestObject();

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

function sxf() {
    q1 = document.getElementById('qth1').value;
    q2 = document.getElementById('qth2').value;
    http.open('get', 'calc.php?q1='+q1+'&q2='+q2);
    http.onreadystatechange = handleResponse;
    http.send(null);
}