XMLHttpRequest status 0 (responseText is empty)

status is 0 when your html file containing the script is opened in the browser via the file scheme. Make sure to place the files in your server (apache or tomcat whatever) and then open it via http protocol in the browser. (i.e. http://localhost/myfile.html) This is the solution.


The cause of your problems is that you are trying to do a cross-domain call and it fails.

If you're doing localhost development you can make cross-domain calls - I do it all the time.

For Firefox, you have to enable it in your config settings

signed.applets.codebase_principal_support = true

Then add something like this to your XHR open code:

  if (isLocalHost()){
    if (typeof(netscape) != 'undefined' && typeof(netscape.security) != 'undefined'){
      netscape.security.PrivilegeManager.enablePrivilege('UniversalBrowserRead');
    }
  }

For IE, if I remember right, all you have to do is enable the browser's Security setting under "Miscellaneous → Access data sources across domains" to get it to work with ActiveX XHRs.

IE8 and above also added cross-domain capabilities to the native XmlHttpRequest objects, but I haven't played with those yet.


Actually make sure your button type is Button not Submit, that caused status conflict where I met recently.


If the server responds to an OPTIONS method and to GET and POST (whichever of them you're using) with a header like:

Access-Control-Allow-Origin: *

It might work OK. Seems to in FireFox 3.5 and rekonq 0.4.0. Apparently, with that header and the initial response to OPTIONS, the server is saying to the browser, "Go ahead and let this cross-domain request go through."