- // Set the correct header, if data is being sent
- if ( s.data )
- xml.setRequestHeader("Content-Type", s.contentType);
+ // Need an extra try/catch for cross domain requests in Firefox 3
+ try {
+ // Set the correct header, if data is being sent
+ if ( s.data )
+ xml.setRequestHeader("Content-Type", s.contentType);
+
+ // Set the If-Modified-Since header, if ifModified mode.
+ if ( s.ifModified )
+ xml.setRequestHeader("If-Modified-Since",
+ jQuery.lastModified[s.url] || "Thu, 01 Jan 1970 00:00:00 GMT" );