Adding an event listener

Question

What is the problem with this js code i can't figure it out. I don't know how to ask it in a question.
https://code.sololearn.com/WpodOJewvFu5/?ref=app

Answer 1

PUT your js code inside
window.onload=function()
{

}

here's a good reference

https://www.sololearn.com/post/7444/?ref=app

Answer 2

「ＨＡＰＰＹ ＴＯ ＨＥＬＰ」, Hima

thank you it worked!