Why am I getting addEventListener error

Question

Please 🥺 someone explain I new to JavaScript

https://code.sololearn.com/WY0a5tpGViS0/?ref=app

Answer 1

Use the "onload" event

window.onload = function() { // Code to be executed };

Put your code in the function

Answer 2

You are getting the error because your javascript is executed BEFORE the browser managed to render the rest of the webpage. So the button element does not exist yet.
And the solution is to delay the execution of the script until the page is loaded. This is what "window.onload" is for, as Chris said, his suggestion will solve your problem.