Question

I am trying my hand at some AJAX for the first time, and am running into an error. I’ve seen some people with similar problems, but after reading through them I still can’t figure out what’s wrong with my code.

The problem I am getting is that rf.getElementsByTagName("motd")[0] is coming up as undefined.

Here’s the code:

function refresh() {
    var url = document.getElementById("url");
    var req;
    if (window.XMLHttpRequest) {
        req = new XMLHttpRequest();
    } else {
        req = new ActiveXObject("Microsoft.XMLHTTP");
    }
    req.onreadystatechange=function() {
        if (req.readyState==4 && req.status==200) {
            var rf;
            if (window.DOMParser) {
                parser = new DOMParser();
                rf=parser.parseFromString(req,"text/xml");
            } else {
                rf = new ActiveXObject("Microsoft.XMLDOM");
                rf.async = false;
                rf.loadXML(req); 
            }
            document.getElementById("result").innerHTML="<div id=\"success\">"+
            rf.getElementsByTagName("motd")[0]+"&nbsp;";
        } else {
            document.getElementById("result").innerHTML="<div id=\"working\">Checking...</div>";
        }
    }
    req.open("POST","g2mc_status.php",true);
    req.send("server="+url);
}

And the XML I am trying to process (which is all the .php file is set to output right now):

<minecraft server="mc.nrd.li" port="25565">
    <motd>NerdConglomerate</motd>
    <players>
        <online>0</online>
        <maximum>20</maximum>
    </players>
</minecraft>

Answer 1

You are passing req instead of req.responseText or req.responseXML to the XML parser.

Works fine otherwise: http://jsfiddle.net/cLGGZ/