The onclick button is not functioning, any idea what might have caused this?

Question

https://code.sololearn.com/W7Zha2qqw2ZB/?ref=app

Answer 1

It's the usual problem here of JavaScript running before the HTML is fully loaded.
To fix it, simply encase everything in the JavaScript tab within:

window.onload = function(){

All of your current JavaScript here

}

That will cause the JavaScript to not run until the HTML is fully loaded and so fixes that error.

Answer 2

Thank you very much