Can anyone explain me,why I am getting error in my JavaScript ?

Question

https://code.sololearn.com/WC1PheY79x46/?ref=app

Answer 1

The javascript is loaded before HTML, which means you cannot just write
let bg = document.getElementById("bg").
If you use a console.log(bg) inside your function, you will see that bg = null.
Search on the internet how to use window.onload=function(){
//your code that should load after html
}

Answer 2

🍇 Alex Tușinean 💜 what do u mean by "code that should load after html" ?

Answer 3

You can not acces any html element with js before it loads. The javascript loads first, so if you try to select a html element, like a paragraph, it will fail, because it won t find any html p

Answer 4

🍇 Alex Tușinean 💜 oo yes,I had done such a dumb mistake🥲,Thank you so much🙂