Concat not working in browser

Question

I have this simple concat calculation in my form. It works perfectly in the Survey123 application but in the browser (and experience builder) it does not. It fills all values with NaN. Can anyone tell me how to fix?

I also already tried setting the calcualtionMode="always"

dougbrowning · Accepted Answer

That is because you are also using +.  The browser does not like + at all.

concat takes multiple arguments so just do

concat(string(${StudyNumber}), "-", string(${TrialID}))

hope that helps