Why this code throw an error???

Question

https://code.sololearn.com/WU0cY8xTAFYI/?ref=app

Answer 1

https://code.sololearn.com/Wn1pZtZoqV5F/?ref=app
One typo: Listener
And wrap an online around your code.

Answer 2

First theres a typo. Listner instead of Listener
And to test js in sololearn u should wrap ur code in
window.onload = () =>{
//code here
};