Sticky Sidebar jQuery

stickySidebar.js

var $sticky = $('.sticky');
var $stickyrStopper = $('.sticky-stopper');
if (!!$sticky.offset()) { // make sure ".sticky" element exists

  var generalSidebarHeight = $sticky.innerHeight();
  var stickyTop = $sticky.offset().top;
  var stickOffset = 120;
  var stickyStopperPosition = $stickyrStopper.offset().top;
  var stopPoint = stickyStopperPosition - generalSidebarHeight - stickOffset;
  var diff = stopPoint + stickOffset;
  
  $(window).scroll(function(){ // scroll event
    var windowTop = $(window).scrollTop(); // returns number
    
    if (stopPoint < windowTop) {
        $sticky.css({ position: 'absolute', top: diff });
    } else if (stickyTop < windowTop+stickOffset) {
        $sticky.css({ position: 'fixed', top: stickOffset });
    } else {
        $sticky.css({position: 'absolute', top: 'initial'});
    }
  });

}