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 sndReq() {
    var date = new Date();
    var time = date.getTime();
    http.open('get', 'whatson.php?trash='+time);
    http.onreadystatechange = handleResponse;
    http.send(null);
    setTimeout("sndReq()", 30000);
}

function handleResponse() {
    if(http.readyState == 4){
        var response = http.responseText;
        if (response != responseold || responsecheck != 1) {
            var responsecheck = 1;
            document.getElementById("messages").innerHTML = http.responseText;
            var responseold = response;
        }
    }
}