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Scroll Tracking GTM
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<script> | |
/*! | |
* @preserve | |
* jquery.scrolldepth.js | v1.0 | |
* Copyright (c) 2016 Rob Flaherty (@robflaherty) | |
* Licensed under the MIT and GPL licenses. | |
*/ | |
/* Universal module definition */ | |
(function(factory) { | |
if (typeof define === 'function' && define.amd) { | |
// AMD | |
define(['jquery'], factory); | |
} else if (typeof module === 'object' && module.exports) { | |
// CommonJS | |
module.exports = factory(require('jquery')); | |
} else { | |
// Browser globals | |
factory(jQuery); | |
} | |
}(function($) { | |
/* Scroll Depth */ | |
"use strict"; | |
var defaults = { | |
minHeight: 0, | |
elements: [], | |
percentage: true, | |
userTiming: true, | |
pixelDepth: false, | |
nonInteraction: false, | |
gaGlobal: false, | |
gtmOverride: false, | |
trackerName: false, | |
dataLayer: 'dataLayer' | |
}; | |
var $window = $(window), | |
cache = [], | |
scrollEventBound = false, | |
lastPixelDepth = 0, | |
universalGA, | |
classicGA, | |
gaGlobal, | |
standardEventHandler; | |
/* | |
* Plugin | |
*/ | |
$.scrollDepth = function(options) { | |
var startTime = +new Date; | |
options = $.extend({}, defaults, options); | |
// Return early if document height is too small | |
if ( $(document).height() < options.minHeight ) { | |
return; | |
} | |
/* | |
* Determine which version of GA is being used | |
* "ga", "__gaTracker", _gaq", and "dataLayer" are the possible globals | |
*/ | |
if (options.gaGlobal) { | |
universalGA = true; | |
gaGlobal = options.gaGlobal; | |
} else if (typeof ga === "function") { | |
universalGA = true; | |
gaGlobal = 'ga'; | |
} else if (typeof __gaTracker === "function") { | |
universalGA = true; | |
gaGlobal = '__gaTracker'; | |
} | |
if (typeof _gaq !== "undefined" && typeof _gaq.push === "function") { | |
classicGA = true; | |
} | |
if (typeof options.eventHandler === "function") { | |
standardEventHandler = options.eventHandler; | |
} else if (typeof window[options.dataLayer] !== "undefined" && typeof window[options.dataLayer].push === "function" && !options.gtmOverride) { | |
standardEventHandler = function(data) { | |
window[options.dataLayer].push(data); | |
}; | |
} | |
/* | |
* Functions | |
*/ | |
function sendEvent(action, label, scrollDistance, timing) { | |
var command = options.trackerName ? (options.trackerName + '.send') : 'send'; | |
if (standardEventHandler) { | |
standardEventHandler({'event': 'ScrollDistance', 'eventCategory': 'Scroll Depth', 'eventAction': action, 'eventLabel': label, 'eventValue': 1, 'eventNonInteraction': options.nonInteraction}); | |
if (options.pixelDepth && arguments.length > 2 && scrollDistance > lastPixelDepth) { | |
lastPixelDepth = scrollDistance; | |
standardEventHandler({'event': 'ScrollDistance', 'eventCategory': 'Scroll Depth', 'eventAction': 'Pixel Depth', 'eventLabel': rounded(scrollDistance), 'eventValue': 1, 'eventNonInteraction': options.nonInteraction}); | |
} | |
if (options.userTiming && arguments.length > 3) { | |
standardEventHandler({'event': 'ScrollTiming', 'eventCategory': 'Scroll Depth', 'eventAction': action, 'eventLabel': label, 'eventTiming': timing}); | |
} | |
} else { | |
if (universalGA) { | |
window[gaGlobal](command, 'event', 'Scroll Depth', action, label, 1, {'nonInteraction': options.nonInteraction}); | |
if (options.pixelDepth && arguments.length > 2 && scrollDistance > lastPixelDepth) { | |
lastPixelDepth = scrollDistance; | |
window[gaGlobal](command, 'event', 'Scroll Depth', 'Pixel Depth', rounded(scrollDistance), 1, {'nonInteraction': options.nonInteraction}); | |
} | |
if (options.userTiming && arguments.length > 3) { | |
window[gaGlobal](command, 'timing', 'Scroll Depth', action, timing, label); | |
} | |
} | |
if (classicGA) { | |
_gaq.push(['_trackEvent', 'Scroll Depth', action, label, 1, options.nonInteraction]); | |
if (options.pixelDepth && arguments.length > 2 && scrollDistance > lastPixelDepth) { | |
lastPixelDepth = scrollDistance; | |
_gaq.push(['_trackEvent', 'Scroll Depth', 'Pixel Depth', rounded(scrollDistance), 1, options.nonInteraction]); | |
} | |
if (options.userTiming && arguments.length > 3) { | |
_gaq.push(['_trackTiming', 'Scroll Depth', action, timing, label, 100]); | |
} | |
} | |
} | |
} | |
function calculateMarks(docHeight) { | |
return { | |
'25%' : parseInt(docHeight * 0.25, 10), | |
'50%' : parseInt(docHeight * 0.50, 10), | |
'75%' : parseInt(docHeight * 0.75, 10), | |
// Cushion to trigger 100% event in iOS | |
'100%': docHeight - 5 | |
}; | |
} | |
function checkMarks(marks, scrollDistance, timing) { | |
// Check each active mark | |
$.each(marks, function(key, val) { | |
if ( $.inArray(key, cache) === -1 && scrollDistance >= val ) { | |
sendEvent('Percentage', key, scrollDistance, timing); | |
cache.push(key); | |
} | |
}); | |
} | |
function checkElements(elements, scrollDistance, timing) { | |
$.each(elements, function(index, elem) { | |
if ( $.inArray(elem, cache) === -1 && $(elem).length ) { | |
if ( scrollDistance >= $(elem).offset().top ) { | |
sendEvent('Elements', elem, scrollDistance, timing); | |
cache.push(elem); | |
} | |
} | |
}); | |
} | |
function rounded(scrollDistance) { | |
// Returns String | |
return (Math.floor(scrollDistance/250) * 250).toString(); | |
} | |
function init() { | |
bindScrollDepth(); | |
} | |
/* | |
* Public Methods | |
*/ | |
// Reset Scroll Depth with the originally initialized options | |
$.scrollDepth.reset = function() { | |
cache = []; | |
lastPixelDepth = 0; | |
$window.off('scroll.scrollDepth'); | |
bindScrollDepth(); | |
}; | |
// Add DOM elements to be tracked | |
$.scrollDepth.addElements = function(elems) { | |
if (typeof elems == "undefined" || !$.isArray(elems)) { | |
return; | |
} | |
$.merge(options.elements, elems); | |
// If scroll event has been unbound from window, rebind | |
if (!scrollEventBound) { | |
bindScrollDepth(); | |
} | |
}; | |
// Remove DOM elements currently tracked | |
$.scrollDepth.removeElements = function(elems) { | |
if (typeof elems == "undefined" || !$.isArray(elems)) { | |
return; | |
} | |
$.each(elems, function(index, elem) { | |
var inElementsArray = $.inArray(elem, options.elements); | |
var inCacheArray = $.inArray(elem, cache); | |
if (inElementsArray != -1) { | |
options.elements.splice(inElementsArray, 1); | |
} | |
if (inCacheArray != -1) { | |
cache.splice(inCacheArray, 1); | |
} | |
}); | |
}; | |
/* | |
* Throttle function borrowed from: | |
* Underscore.js 1.5.2 | |
* http://underscorejs.org | |
* (c) 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors | |
* Underscore may be freely distributed under the MIT license. | |
*/ | |
function throttle(func, wait) { | |
var context, args, result; | |
var timeout = null; | |
var previous = 0; | |
var later = function() { | |
previous = new Date; | |
timeout = null; | |
result = func.apply(context, args); | |
}; | |
return function() { | |
var now = new Date; | |
if (!previous) previous = now; | |
var remaining = wait - (now - previous); | |
context = this; | |
args = arguments; | |
if (remaining <= 0) { | |
clearTimeout(timeout); | |
timeout = null; | |
previous = now; | |
result = func.apply(context, args); | |
} else if (!timeout) { | |
timeout = setTimeout(later, remaining); | |
} | |
return result; | |
}; | |
} | |
/* | |
* Scroll Event | |
*/ | |
function bindScrollDepth() { | |
scrollEventBound = true; | |
$window.on('scroll.scrollDepth', throttle(function() { | |
/* | |
* We calculate document and window height on each scroll event to | |
* account for dynamic DOM changes. | |
*/ | |
var docHeight = $(document).height(), | |
winHeight = window.innerHeight ? window.innerHeight : $window.height(), | |
scrollDistance = $window.scrollTop() + winHeight, | |
// Recalculate percentage marks | |
marks = calculateMarks(docHeight), | |
// Timing | |
timing = +new Date - startTime; | |
// If all marks already hit, unbind scroll event | |
if (cache.length >= options.elements.length + (options.percentage ? 4:0)) { | |
$window.off('scroll.scrollDepth'); | |
scrollEventBound = false; | |
return; | |
} | |
// Check specified DOM elements | |
if (options.elements) { | |
checkElements(options.elements, scrollDistance, timing); | |
} | |
// Check standard marks | |
if (options.percentage) { | |
checkMarks(marks, scrollDistance, timing); | |
} | |
}, 500)); | |
} | |
init(); | |
}; | |
// UMD export | |
return $.scrollDepth; | |
})); | |
jQuery(function() { | |
jQuery.scrollDepth(); | |
}); | |
</script> |
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