Thanks for the response. I had originally placed the expression and the JS to bubble elements into the popup and it was at that point I first got the error message.
I then went back and tested on a page and it was not working at that point, although it previously had.
The input element had been on the page the entire time.
I had actually gotten help from @tim12333 and he was kind enough to get it working on another app. From there I copied all the code etc. into the app I linked above. It was working, and after testing several times, I posted in the forum how to do it, as I was at that point confident it was all set up correctly and working properly.
Then when putting it into another app on a page it worked, but then I tried in a popup and everything seemed to get all messed up. Went back to the app I linked and noticed the error message there at that point too.
So I created another test app…
https://bubble.io/page?name=index&id=testjscapson&tab=tabs-1
I am not getting the error message on this one, however the functionality just doesn’t work at all.
All very strange to me as I know nothing of JavaScript and just naturally assumed if I set things up the same exact way it should be working, but nonetheless it isn’t and I’m lost on the issue.