GM_xmlhttpRequest responseText empty in Firefox but perfect in Chrome

Question

I'm trying to do a userscript for Chrome and Greasemonkey in Firefox.

I'm using the GM_xmlhttpRequest since it supposed to work in both platforms. The request code seems to work in both browsers, but in Firefox the responseText is empty in contrast to Chrome where I get the expected response.

The userscriptcode:

// ==UserScript==  
// @include        *.website.org/Forum/Read.aspx?*  
// ==/UserScript==

        getstr = "thread="+thread+"&day="+getday;
    GM_xmlhttpRequest({
        method: "POST",
        url: "http://www.other.org/js/gm/get.php",
        data: getstr,
        headers: {
            "Content-Type": "application/x-www-form-urlencoded",
            "Content-type":"charset=utf-8"
        },
        onload: function(response) {
                        alert(response.responseText);
        }
    });

The php-script on the "other.org" site:

    $json = json_encode($array);
    echo $json;

The userscript handles the response with a JSON.parse(), but that is not important here.

In chrome, this works perfectly, but the responseText is empty in firefox.

I have read about that this might be something to do with the same-origin policies. But I don't understand how this might be and how I can fix it. All help is very welcome!

It actually doesn't seem to post the data at all. The onload function is activated anyway. The empty responseText may be because the php-script doesn't get any data to process. — Juniperus, Jan 15 '12 at 15:20
Objects can't have multiple properties with identical names. Put the charset into the first `Content-Type`. Also, try adding more headers, `Content-Length`, specifically. The safest bet is to inspect what headers Firefox sends on normal POST-requests (when you submit the form manually) and copy them all. — katspaugh, Jan 15 '12 at 15:58
Juniperus, no problem. What exactly solved your question, eliminating duplicate header properties? — katspaugh, Jan 15 '12 at 16:37
Yes. I added the charset to the first content type instead of having two. Thanks again! — Juniperus, Jan 20 '12 at 00:03

score 3 · Accepted Answer · answered Jan 15 '12 at 16:36

Objects can't have multiple properties with identical names. Put the charset header value into the first Content-Type.

Also, try adding more headers, Content-Length, specifically. The safest bet is to inspect what headers Firefox sends on normal POST-requests (when you submit the form manually) and copy them all.

GM_xmlhttpRequest responseText empty in Firefox but perfect in Chrome

1 Answers1