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I have a a form that I am submitting via ajax. I am using the jquery form plugin. What I am trying to do is get the 'Location' header which is returned from my server. I can see it in firebug. But whenever I call the getResponseHeader() function in my success callback, it always returns 'undefined'..

Code: 

form.ajaxForm({ dataType: 'xml', data: {format: 'xml'}, resetForm: true, success: function(xml,status,xhr){ var location = xhr.getResponseHeader('Location'); alert(location); });

location is undefined. But I can see the 'Location' header in firebug. What am I missing? Even if I call getAllResponseHeaders() from the xhr object, it returns 'undefined'

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  • Just to add: This has been tested in both firefox and opera. Same results Commented Dec 6, 2010 at 19:22

3 Answers 3

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38

If this is a CORS request, you may see all headers in debug tools (such as Chrome->Inspect Element->Network), but the xHR object will only retrieve the header (via xhr.getResponseHeader('Header')) if such a header is a simple response header:

  • Content-Type
  • Last-modified
  • Content-Language
  • Cache-Control
  • Expires
  • Pragma

If it is not in this set, it must be present in the Access-Control-Expose-Headers header returned by the server.

About the case in question, if it is a CORS request, one will only be able to retrieve the Location header throgh the XMLHttpRequest object if, and only if, the header below is also present:

Access-Control-Expose-Headers: Location

If its not a CORS request, XMLHttpRequest will have no problem retrieving it.

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1 Comment

This is the correct answer, if you have to use CORS and have these problems.
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An XMLHttpRequest will transparently follow a redirect, so the final request won't have the header, it's already followed that redirect and you're seeing the response headers from that request (not the initial request which had the Location header).

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10 Comments

The server generates a 201 Created response. I sure hope jquery doesn't interpret this as a redirect. And firebug does not show a second request.
@Nik - It has a Location header though, right? that's a redirect.
It does have a location header, but if I understand the http response codes, 30x series means redirect. not 20x. 20x does not imply further action. The location header should be informational. But maybe I am wrong?
@Nik - Do you have a server I can see this on? You're sure the initial response is a 201, the initial one with the Location header...not the second?
After checking my server logs for my ruby on rails application, I do not see a second request after the 201 response. So xhr is not redirecting to the location. That is fine, but maybe jquery is getting confused? Any more ideas? Thanks for your help. ;)
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I'm doing something similar using the rails/rest way of returning a 201 "created" with a Location header to the new object and an empty body. jQuery's ajax method will throw a "parseerror" when encountering this since its expecting json but getting nothing back. I simply catch the 201 redirect in my error callback like so:

function request_error(req, textStatus, errorThrown) { if (req.status == 201 ) { var created_loc = req.getResponseHeader('Location'); console.log('(201) created: ' + created_loc); // ... manual redirect here i.e. issue another ajax request to created_loc return; } // ... handle an actual error here }

hope this helps!

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1 Comment

Just set dataType: 'text' as arg, and you can catch the 201 in the complete callback (or even better: jqXHR.done).

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