javascript - How do i detect when a user is at the top of the webpage

Question

I\'m pretty much completely new to javascript, and I know there\'s already a similar question to this on here, but i would like the script as in.

if (user is at top of

Answer 1

Here's a clean solution that should make sense if you're new to JS:

//call your function on scroll
window.onscroll = myScrollFunction;

function myScrollFunction(){
  if(getYOffset() == 0){
    //if at top, do this
    alert('bingo');

  }
};
//helper function (since ie handles scrolling different than firefox)
function getYOffset() {
    var pageY;
    if(typeof(window.pageYOffset)=='number') {
       pageY=window.pageYOffset;
    }
    else {
       pageY=document.documentElement.scrollTop;
    }
    return pageY;
}