HTTP Header Issue in Mobile Safari Can Break AJAX

January 25th, 2012 Posted by Dave Mahon

Mike Swieton has reported a bug in Mobile Safari on iOS 5.1.

The bug occurs on AJAX-heavy sites that let you download content. Specifically, he experienced it when he clicked to view a PDF inside Mobile Safari and then used the back button to return to the site. Subsequent AJAX requests had the OPTIONS verb instead of the expected GET, something the web server obviously would not expect.

Fortunately, he came up with a fix. If you change the Content-Disposition HTTP header from attachment to inline, the browser does not lose track of the current domain and thus does not change the verb used for AJAX requests.