Javascript detect browser scroll to the top?

Question

How do I modify the following code to detect scrolling to the top page instead.

window.onscroll = function(ev) {
    if ((window.innerHeight + window.scroll         


        

Answer 1

if (document.body.scrollTop == 0 || document.documentElement.scrollTop == 0) 
{
    alert("top");
}

worked for me

https://www.w3schools.com/jsref/event_onscroll.asp