Javascript-Event: Start it when visible in Browser-Window?

Question

i iam looking for a solution for a Problem like this:

Run script when div is visible in browser window

My problem is: My DIV are stacked! You maybe know a solution?

---

EDIT:

I did try it like this: And it works! ... more or less :)

My Problem at the moment:

• If loadcontent() loads fast = it works!
• If it loads slow it doesn't!

Is there some way to solve this?

function checkContentLoad(divId){
  
  if (divId == 'faq')
      { if($('#contentbox-faq').is(':visible'))
      { loadcontent('faq', '0', '0');
      }}
      
  if (divId == 'kontakt')
      { if($('#contentbox-kontakt').is(':visible'))
      { loadcontent('kontakt', '0', '0');
      }}
}

<div id="contentbox-faq" class="contentbox-faq">

<script>
checkContentLoad('faq');
</script>

</div>