var isPnWorking = false;

function getPost(input,evt) {
	if (input.value.length == 0) {
        	return;
    	}
 //allow backspace to work in IE
    if (typeof input.selectionStart == 'undefined' && evt.keyCode == 8) { input.value = input.value.substr(0,input.value.length-1); }

    // Ignore the following keystrokes
    switch (evt.keyCode) {
        case 37: //left arrow
        case 39: //right arrow
        case 33: //page up
        case 34: //page down
        case 36: //home
        case 35: //end
        case 13: //enter
        case 9: //tab
        case 27: //esc
        case 16: //shift
        case 17: //ctrl
        case 18: //alt
        case 20: //caps lock
        case 8: //backspace
        case 46: //delete
        case 38: //up arrow
        case 40: //down arrow
            return;
        break;
    }
	if (!isPnWorking && http) {
		var awsUrl = "/postnr.php?postnr="+input.value;
		http.open('GET', awsUrl);
		http.onreadystatechange = handlePNResponse;
		isPnWorking = true;
		http.send(null);
	}
}
function handlePNResponse() {
	var update = new Array();
	if(http.readyState == 4) {
		if (http.responseText.indexOf('invalid') == -1) {
			isPnWorking = false;
			var xmlDocument = http.responseXML;
			var postnr = xmlDocument.getElementsByTagName('Postnr')[0].firstChild.data;
			var sted = xmlDocument.getElementsByTagName('Sted')[0].firstChild.data;
			document.signup.Sted.value = sted;
			isPnWorking = false;
		}
	}
}
/* primary function to create request object */
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();