biobulkbende.org/app/assets/js/modules/RevealOnScroll.js

import $ from 'jquery';
import waypoints from '../../../../node_modules/waypoints/lib/noframework.waypoints';

 class RevealOnScroll {
 	constructor(els, offset){
 		this.itemsToReveal = els;
 		this.offsetPercentage = offset;
 		this.hideInitially();
 		this.createWaypoints();
 	}
 	
 	hideInitially() { 
 		this.itemsToReveal.addClass("reveal-item");
 	}

 	createWaypoints() {
 		var that = this;
 		this.itemsToReveal.each( function(){
 			var currentItem = this;
 			new Waypoint({
 				element: currentItem,
  				handler: function() {
    				$(currentItem).addClass("reveal-item--is-visible");
  				},
  				offset: that.offsetPercentage
 			});
 		});
 	}
 }

 export default RevealOnScroll;