Google Analytics Scroll Position Tracking

scroll-tracking.js

// Implementation for tracking the vertical scroll of a page and firing events at 25%, 50%, 75%, 100% positions
// Requires jQuery (feel free to fork a version that doesn't!)

var scrollPercentages = {
	scroll25: false,
	scroll50: false,
	scroll75: false,
	scroll100: false
}

$(window).scroll(function(){

	var percentage = ( ( $(document).scrollTop()  + window.innerHeight ) / $(document).height() ) * 100

	if(percentage === 100 && scrollPercentages.scroll100 === false){

		scrollPercentages.scroll100 = true;

		ga('send', 'event', { eventCategory: 'Scroll', eventAction: '100%'});

	} else if(percentage > 75 && scrollPercentages.scroll75 === false){

		scrollPercentages.scroll75 = true;

		ga('send', 'event', { eventCategory: 'Scroll', eventAction: '75%'});

	} else if(percentage > 50 && scrollPercentages.scroll50 === false){

		scrollPercentages.scroll50 = true;

		ga('send', 'event', { eventCategory: 'Scroll', eventAction: '50%'});

	} else if(percentage > 25 && scrollPercentages.scroll25 === false){

		scrollPercentages.scroll25 = true;

		ga('send', 'event', { eventCategory: 'Scroll', eventAction: '25%'});

	};

});