Moved jQuery.ajax.prefilter and jQuery.ajax.transport to jQuery.ajaxPrefilter and jQuery.ajaxTransport so that proxying the ajax method doesn't turn into a nightmare. Thanks go to scott_gonzalez and DaveMethvin for pointing out the issue. Also made ajaxSetup return "this" to enable chainable definitions -- jQuery.ajaxSetup(...).ajaxPrefilter(...).ajaxTransport(...).