JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
  <div id="display"></div>
  <div id="elem">Hello world</div>
</div>

CSS

.wrapper{
  min-height:5000px;
}
#elem{
  margin-top:3000px;
}

#display{
  position:fixed;
  top:0;
  background:#FFF;
}

JavaScript

$(window).scroll(function(){
  $('#display').text(
    $('html,body').scrollTop()>=$('#elem').offset().top?'True':'False'
  );
}).scroll();