My Javascript doesn't work on the smartphone.

Question

I made a small web calculator on my PC. The Code is working on PC, also on Sololearn's Code Playground on PC, but not on Sololearn's Code Playground on the smartphone app.
Does anybody know, which underlying browser Sololearn is using for the web Output on the mobile code playground?
Here's my Code. Sorry, it's a bit messy...
https://code.sololearn.com/WPfRLZjPBju5/?ref=app

Answer 1

it is a WebView, so you can start research from there.
also, which device you have?
the code works for me on galaxy s5

Answer 2

Thank you. I have a galayy s3.

Answer 3

But I dont know. On my brother's phone it is also working.