Google Site Tag integration

Integrations/Analytics/Google Site Tag/.gitignore

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+.DS_STORE

Integrations/Analytics/Google Site Tag/License

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+Copyright 2017 Optimizely Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.

Integrations/Analytics/Google Site Tag/README.md

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+## Prerequisites
+
+This integration is aimed at customers who are using Google Analytics and have transitioned to the new [Google Site Tag tracking code](https://developers.google.com/analytics/devguides/collection/gtagjs/).
+
+The below guide also implies that you plan on using 1 Google Analytics Custom Dimension per experiment. 
+
+This guide also implies that you have also created the Custom Dimensions you plan on using in the Google Analytics interface. 
+
+## Installation
+
+Contrary to analytics.js, the new Global Site Tag tracking code (gtag.js) requires to reference the custom dimensions prior to using them. 
+
+Therefore, in order to use this integration you'll need to update the Global Site Tag and add the list of custom dimensions you want to use to store Optimizely experiment data. 
+
+By default, the Global Site Tag looks like this: 
+
+```javascript
+  window.dataLayer = window.dataLayer || [];
+  function gtag(){dataLayer.push(arguments);}
+  gtag('js', new Date());
+
+  gtag('config', 'GA_TRACKING_ID');
+```
+
+where `GA_TRACKING_ID` is your Google Analytics tracking ID. 
+
+We'll need to update the last line of code to look like this: 
+
+```javascript
+gtag('config', 'GA_TRACKING_ID', {
+  'custom_map': {'dimension<Index>': 'DIMENSION_NAME'}
+});
+```
+
+where `GA_TRACKING_ID` is your Google Analytics tracking ID, `<Index>` is the custom dimension index and `DIMENSION_NAME` the name of the custom dimension. This information can be found by going into your Google Analytics dashboard->Admin->Property->Custom Definitions->Custom Dimensions. 
+
+Note that you need to add each custom dimension you plan on using to store Optimizely data (including the ones that will be used for future experiments). 
+If there are multiple custom dimensions, the code will look like this: 
+
+```javascript
+gtag('config', 'GA_TRACKING_ID', {
+  'custom_map': 
+  {'dimension<Index>': 'DIMENSION_NAME'},
+  {'dimension<Index_2>': 'DIMENSION_NAME_2'},
+  {'dimension<Index_3>': 'DIMENSION_NAME_3'},
+});
+```
+
+Next, go into Optimizely, head to the experiment that you want to integrate Google Site Tag with. 
+
+Turn on the Google Site Tag Custom Analytics extension and in the experiment integration settings, enter the Custom Dimension name as you see it in the Google Analytics interface. 
+
+Save and you should be good to go!

Integrations/Analytics/Google Site Tag/config.json

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+{
+    "plugin_type": "analytics_integration",
+    "name": "Google Site Tag Integration",
+    "form_schema": [
+      {
+        "default_value": "",
+        "field_type": "text",
+        "name": "dimension_name",
+        "label": "Custom Dimension Name",
+        "options": null
+      }
+    ],
+    "description": "",
+    "options": {
+      "track_layer_decision": "/*\n * Javascript written in this tab will run every time a user is\n * assigned to an experiment and variation, but before any experiment\n * code runs. This hook is useful for tracking which variations a\n * visitor has been assigned to. Click the help icon for more information.\n */\n\nvar decisionString = optimizely.get('state').getDecisionString({\n  campaignId: campaignId,\n  shouldCleanString: true,\n  maxLength: 255\n});\n\nif(!!decisionString) {\n    optimizely.get('utils').waitUntil(function() {\n      return window.gtag !== undefined\n    }).then(function() {\n        var payload = {};\n        payload[extension['dimension_name']] = decisionString;\n        payload['event_category'] = decisionString;\n        gtag('event', 'Optimizely Experiment', payload);\n    }); \n}\n"
+    }
+  }

Integrations/Analytics/Google Site Tag/integration.js

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+/*
+ * Javascript written in this tab will run every time a user is
+ * assigned to an experiment and variation, but before any experiment
+ * code runs. This hook is useful for tracking which variations a
+ * visitor has been assigned to. Click the help icon for more information.
+ */
+
+var decisionString = optimizely.get('state').getDecisionString({
+  campaignId: campaignId,
+  shouldCleanString: true,
+  maxLength: 255
+});
+
+if(!!decisionString) {
+    optimizely.get('utils').waitUntil(function() {
+      return window.gtag !== undefined
+    }).then(function() {
+        var payload = {};
+        payload[extension['dimension_name']] = decisionString;
+        payload['event_category'] = decisionString;
+        gtag('event', 'Optimizely Experiment', payload);
+    }); 
+}