How to deal with this error in the console?

Question

JavaScript

There is a site that gives such an error in Chrome.

On closer examination, claims to this fragment:

It is clear that the point is that the value is undefined, but I just can’t figure out what exactly he doesn’t like and how to fix it?

Answer 1

self.element has an empty set of elements, so the val method returns undefined instead of the string you expect.
You can fix it by slipping an empty string instead of undefined:
(self.element.val() || '')