I have problems with my Javascript code

Question

I have made a small reaction test game.
Curiously if I try it locally on my PC in Firefox and Chrome it is working fine, but within the player of sololearn I got errors thrown, and it is not working at all.
Does anybody have a idea of my fault?

Thanks

Here is the code:
https://code.sololearn.com/WjePfIGf2ubH

Answer 1

do you mean "cannot set onclick property..."?
then you just have to put your javascript code after your html text inside script tag, or you can just wrap your code inside window onload event
that happen because your js code gets executed first before your html file

Answer 2

Ahhh Great, that is why it worked on my local system, there I had the script also located under the body.
Now it is working fine!

Thanks!