Grab jQuery set CSS class
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My scenario is this:

I'm runing Contact Form 7 (contactform7.com). When a user have'nt set the required fields and pressed send (the form is sent with jQuery, so a page reload is'nt initiated) the Contact Form 7 script outputs a "error class" to the input field where the user have missed to fill out.

This class - which the Contact Form 7 have set - I want to grab. But it seems that hasClass() does'nt work on this. It just works on predefined classes. 

My conclusion is that the class which hasClass() tries to grab is'nt available at some how when the whole page is'nt reloaded.

How do I solve this and can be able to grab the class?