All this is done in Chrome Version 25.0.1364.29 beta-m, and results in other browsers or versions have not been tested.

In the latest version (1.9.0) of jQuery the parseJSON function has been changed from the previous version (1.8.3).

jquery.validate.unobtrusive.js (latest version (2.0.20710.0) included in the latest ASP.NET MVC package) utilizes this function, in some cases it makes a call that is basically broken down to this:

$.parseJSON(undefined)

(which I guess is bad practice? and if so should be reported to them also)

Anyway, making such a call in jQuery 1.8.3 or earlier returned null.

While in jQuary 1.9.0 it will return an error.

undefined is kind of a special case so maybe this is considered as ok?

Anyway my question is, since parseJSON behaves differently in the latest version from earlier versions, should this be considered as a bug and be reported?