How can I get rid of this error.

Question

I'm working with a project which has a few buttons with EventListeners. But my buttons aren't working & in the console I'm getting this error,
"Cannot read property addEventListeners of null".
Although I put my js code at the bottom of the document. Please someone help me.

Answer 1

// Can you try this code below. It should work:

window.onload = function() {
document.getElementById("btn").addEventListener("click", myFunction);
}

function myFunction() {
alert("hello");
}

Answer 2

Could you please show the code

Answer 3

https://code.sololearn.com/Wbnn57whft69/?ref=app

This isn't the actual project code but, I'm getting this same error.

Answer 4

Sorry, but it's not working.
I'm still getting that error.

https://code.sololearn.com/Wbnn57whft69/?ref=app

Answer 5

The problem is the id is not the same as the element in HTML
So it should be:

document.getElementById("btn")

not

document.getElementById("demo")