Why doesnt work?

Question

I am new to JS.
Could you tell me why getElementById returns null in my code?
https://code.sololearn.com/WowXLP1nO5qU/?ref=app

Answer 1

Because the document isn't loaded when you try to get the element.
Use this instead:
window.onload = function() {
cir();
}

This will wait for the document to load before doing anything