Merge pull request #294 from ikennaokpala/accomodate-multiple-custom-…

…dimensions

Allow use of multiple `customDimensionIndex` option

docs/javascript.md

@@ -264,6 +264,24 @@ var test = new GOVUK.MultivariateTest({
 
 `customDimensionIndex` is the index of the custom variable in Google Analytics. GA only gives 50 integer slots to each account, and it is important that a unique integer is assigned to each test. Current contact for assigning a custom var slot for GOV.UK is: Tim Leighton-Boyce <[email protected]>
 
+For certain types of tests where the custom dimensions in Google Analytics can only have one of three scopes (hit, session, or user). Measuring performance of A/B tests, and want to compare test results for session-scoped custom dimensions (eg: index 222) against hit-scoped ones (eg: index 223) may become important.
+
+Instead of supplying an integer (like the above example), `customDimensionIndex` can also accept an array of dimension indexes ([222, 223]), see below for more.
+
+Make sure to check GA debugger that these values are being sent before deploying.
+
+```js
+var test = new GOVUK.MultivariateTest({
+  name: 'car_tax_button_text',
+  customDimensionIndex: [222, 223],
+  cohorts: {
+    pay_your_car_tax: {weight: 25},
+    give_us_money: {weight: 50}
+  }
+});
+```
+
+
 ## Primary Links
 
 `GOVUK.PrimaryList` hides elements in a list which don't have a supplied

javascripts/govuk/multivariate-test.js

@@ -76,14 +76,23 @@
   };
 
   MultivariateTest.prototype.setCustomVar = function(cohort) {
-    if (this.customDimensionIndex) {
-      GOVUK.analytics.setDimension(
-        this.customDimensionIndex,
-        this.cookieName() + "__" + cohort
-      );
+    if (this.customDimensionIndex &&
+      this.customDimensionIndex.constructor === Array) {
+      for (var index = 0; index < this.customDimensionIndex.length; index++) {
+        this.setDimension(cohort, this.customDimensionIndex[index])
+      }
+    } else if (this.customDimensionIndex) {
+      this.setDimension(cohort, this.customDimensionIndex)
     }
   };
 
+  MultivariateTest.prototype.setDimension = function(cohort, dimension) {
+    GOVUK.analytics.setDimension(
+      dimension,
+      this.cookieName() + "__" + cohort
+    );
+  };
+
   MultivariateTest.prototype.setUpContentExperiment = function(cohort) {
     var contentExperimentId = this.contentExperimentId;
     var cohortVariantId = this.cohorts[cohort]['variantId'];

spec/unit/multivariate-test.spec.js

@@ -63,6 +63,26 @@ describe("MultivariateTest", function() {
       );
     });
 
+    it("should be able to set multiple custom vars with the name and cohort if one is defined as an array", function() {
+      GOVUK.cookie.and.returnValue('foo');
+      var test = new GOVUK.MultivariateTest({
+        name: 'stuff',
+        cohorts: {
+          foo: {},
+          bar: {}
+        },
+        customDimensionIndex: [2,3]
+      });
+      expect(GOVUK.analytics.setDimension).toHaveBeenCalledWith(
+        2,
+        'multivariatetest_cohort_stuff__foo'
+      );
+      expect(GOVUK.analytics.setDimension).toHaveBeenCalledWith(
+        3,
+        'multivariatetest_cohort_stuff__foo'
+      );
+    });
+
     it("should trigger an event to track that the test has been run", function() {
       GOVUK.cookie.and.returnValue('foo');
       var test = new GOVUK.MultivariateTest({