https://blog.mozilla.org/wp-content/mu-plugins/mozilla-custom/ga-snippet.js?ver=.4

1/* This Source Code Form is subject to the terms of the Mozilla Public
2 * License, v. 2.0. If a copy of the MPL was not distributed with this
3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
4
5// create namespace
6if (typeof Mozilla === 'undefined') {
7    var Mozilla = {};
8}
9
10/**
11 * Returns true or false based on whether doNotTrack is enabled. It also takes into account the
12 * anomalies, such as !bugzilla 887703, which effect versions of Fx 31 and lower. It also handles
13 * IE versions on Windows 7, 8 and 8.1, where the DNT implementation does not honor the spec.
14 * @see https://bugzilla.mozilla.org/show_bug.cgi?id=1217896 for more details
15 * @params {string} [dnt] - An optional mock doNotTrack string to ease unit testing.
16 * @params {string} [ua] - An optional mock userAgent string to ease unit testing.
17 * @returns {boolean} true if enabled else false
18 */
19Mozilla.dntEnabled = function(dnt, ua) {
20    'use strict';
21
22    // for old version of IE we need to use the msDoNotTrack property of navigator
23    // on newer versions, and newer platforms, this is doNotTrack but, on the window object
24    // Safari also exposes the property on the window object.
25    var dntStatus = dnt || navigator.doNotTrack || window.doNotTrack || navigator.msDoNotTrack;
26    var userAgent = ua || navigator.userAgent;
27
28    // List of Windows versions known to not implement DNT according to the standard.
29    var anomalousWinVersions = ['Windows NT 6.1', 'Windows NT 6.2', 'Windows NT 6.3'];
30
31    var fxMatch = userAgent.match(/Firefox\/(\d+)/);
32    var ieRegEx = /MSIE|Trident/i;
33    var isIE = ieRegEx.test(userAgent);
34    // Matches from Windows up to the first occurance of ; un-greedily
35    // http://www.regexr.com/3c2el
36    var platform = userAgent.match(/Windows.+?(?=;)/g);
37
38    // With old versions of IE, DNT did not exist so we simply return false;
39    if (isIE && typeof Array.prototype.indexOf !== 'function') {
40        return false;
41    } else if (fxMatch && parseInt(fxMatch[1], 10) < 32) {
42        // Can't say for sure if it is 1 or 0, due to Fx bug 887703
43        dntStatus = 'Unspecified';
44    } else if (isIE && platform && anomalousWinVersions.indexOf(platform.toString()) !== -1) {
45        // default is on, which does not honor the specification
46        dntStatus = 'Unspecified';
47    } else {
48        // sets dntStatus to Disabled or Enabled based on the value returned by the browser.
49        // If dntStatus is undefined, it will be set to Unspecified
50        dntStatus = { '0': 'Disabled', '1': 'Enabled' }[dntStatus] || 'Unspecified';
51    }
52
53    return dntStatus === 'Enabled' ? true : false;
54};
55
56(function() {
57    'use strict';
58
59    var blogName = document.querySelector('meta[name="blog-name"][content]').content;
60
61    // If doNotTrack is not enabled, it is ok to add Google Analytics
62    // @see https://bugzilla.mozilla.org/show_bug.cgi?id=1217896 for more details
63    if (typeof Mozilla.dntEnabled === 'function' && !Mozilla.dntEnabled() && blogName) {
64        var measurementId = 'G-X4N05QV93S';
65
66        (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':
67        new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],
68        j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src=
69        'https://www.googletagmanager.com/gtag/js?id='+i+dl;f.parentNode.insertBefore(j,f);
70        })(window,document,'script','dataLayer',measurementId);
71
72        window.dataLayer = window.dataLayer || [];
73        window.gtag = function(){dataLayer.push(arguments);}
74        gtag('js', new Date());
75
76        gtag('config', measurementId);
77    }
78})();