I have several jquery based ajax calls that work w/o issue. However one fairly complex one returns an error even with a successful response from the call. The error is on this line:

if ( fn.apply( obj[i], args [i, obj[i]] ) === false ) break;

where fn is void.

It was pointed out on the forum that using:

if ( fn&&fn.apply( obj[i], args [i, obj[i]] )) break;

would check if fn was void, and break rather than throwing an exception. Using this line in my code, the problem ajax call now works, as does all of my existing ajax calls.

I wish I could tell you why fn is void, which may be the real bug, but it seems reasonable to test if fn is void and break.