window.onload = initPage;



function initPage() {
	myInterval = setInterval(checkStatus,3000);
	checkStatus();
}




function checkStatus() {
    request = createRequest();

  	if (request == null) {
    	alert("Unable to create request");
    	return;
  	}
	var url= "ChatAvailable.php";
  	request.open("GET", url, true);
  	request.onreadystatechange = checkResults;
  	request.send(null);
}



 
function checkResults() {
	if (request.readyState == 4) {
    	if (request.status == 200) {
    		var response = request.responseText;
            
			if (response == "available") {
				var button = "http://www.volunteerlogin.org/chat/chatavailable.gif";
			} else if (response == "busy") {
				var button = "http://www.volunteerlogin.org/chat/chatbusy.gif";
			} else {
				var button = "http://www.volunteerlogin.org/chat/chatunavailable.gif";
			}
		document.getElementById("ChatButton").setAttribute("src",button);
		}
	} 
}





function createRequest() {
    try {
        request = new XMLHttpRequest();
        } catch (tryMS) {
            try {
                request = new ActiveXObject("Msxml2.XMLHTTP"); 
                } catch (otherMS) {
                    try {
                        request = new ActiveXObject("Microsoft.XMLHTTP"); 
                    } catch (failed) {
                request = null;
            }
        }    
    }
  return request;
}