var xmlHttp

function getprice() {
	xmlHttp=GetXmlHttpObject();

	if (xmlHttp==null) {
		alert('Giving up :( Cannot create an XMLHTTP instance. Something is borked.');
		return;
	}


	if ((document.getElementById('sel_type').value == 'r') || (document.getElementById('sel_type').value == 'r2')) {

		var type='r';
		if (document.getElementById('sel_quantity').value >= 3) {
			var type='r2';
		} 
	} else if ((document.getElementById('sel_type').value == 'w') || (document.getElementById('sel_type').value == 'w2')) {
		var type='w';
		if (document.getElementById('sel_quantity').value >= 6) {
			var type='w2';
		}
	}

	var size=document.getElementById('sel_size').value;
	var url="getprice.php?size=" +  size + "&type=" + type;
	xmlHttp.onreadystatechange=  function() {
		if (xmlHttp.readyState==4) {
			document.getElementById('price').innerHTML=xmlHttp.responseText;
		}
	}
	xmlHttp.open("GET",url,true);
	xmlHttp.send(null);
}

function GetXmlHttpObject() {
	var xmlHttp=null;
	try {
		// Firefox, Opera 8.0+, Safari, IE7
		xmlHttp=new XMLHttpRequest();
	}
	catch (e) {
		// IE6 and under
		try {
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e) {
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	return xmlHttp;
}