why I'm getting this error in js console... in where other editor can play this without error.. but solorlearn is giving me erro

Question

JavaScript Console
Uncaught TypeError: Cannot read property 'addEventListener' of null
Line: 9Uncaught TypeError: Cannot read property 'style' of null
Line: 12
link of my code is here:
https://code.sololearn.com/W4CABL65B7ch/#js

Answer 1

add your js code in this function

window.onload=function(){
all js code goes here
}

You can read about it on net, what it does and search for similar answers

Answer 2

Probably this helps ,it shows the support for different browser ,scroll to the bottom
https://developer.mozilla.org/en-US/docs/Web/API/EventTarget/addEventListener

Answer 3

probably that might be the reason

Answer 4

Abhay thanks for your answer;;; but it doesn't work.. I am contually getting the error..

Answer 5

well, that is the reason may be;

The addEventListener() method is not supported in Internet Explorer 8 and earlier versions.

Answer 6

Thanks bro.. I have looked it... but can't get anything of it...
so much text for a simple explanation...