This script calls a function when scrolling 90px from end of the screen.

scrollLoad.js

var mLock = true;
$(window).scroll(function(){
	   if (document.body.scrollHeight <= document.body.scrollTop + window.innerHeight + 90 ){
		   if(mLock){
		       mLock = false;
          doSomeFunction();
		   }
	   }
});

doSomeFunction(){
// crazy loading content via ajax and stuff

  mLock = true;
}