[Amplitude] Send Referrer Information Inside Integration (#73)

* send referrer info

* formatting

Author: jlee9595

integrations/amplitude/lib/index.js

@@ -69,7 +69,6 @@ Amplitude.prototype.initialize = function() {
 
   window.amplitude.getInstance().init(this.options.apiKey, null, {
     includeUtm: this.options.trackUtmProperties,
-    includeReferrer: this.options.trackReferrer,
     batchEvents: this.options.batchEvents,
     eventUploadThreshold: this.options.eventUploadThreshold,
     eventUploadPeriodMillis: this.options.eventUploadPeriodMillis,
@@ -126,6 +125,8 @@ Amplitude.prototype.loaded = function() {
 Amplitude.prototype.page = function(page) {
   this.setDeviceIdFromAnonymousId(page);
 
+  if (this.options.trackReferrer) this.sendReferrer();
+
   var category = page.category();
   var name = page.fullName();
   var opts = this.options;
@@ -392,6 +393,31 @@ Amplitude.prototype.setRevenue = function(properties) {
   }
 };
 
+// equivalent of sending includeReferrer=true in the amplitude config object when we initialize
+Amplitude.prototype.sendReferrer = function() {
+  var identify = new window.amplitude.Identify();
+
+  var referrer = this.getReferrer();
+  if (!referrer || referrer.length === 0) return;
+
+  identify.setOnce('initial_referrer', referrer);
+  identify.set('referrer', referrer);
+
+  var parts = referrer.split('/');
+  if (parts.length >= 3) {
+    var referring_domain = parts[2];
+    identify.setOnce('initial_referring_domain', referring_domain);
+    identify.set('referring_domain', referring_domain);
+  }
+
+  window.amplitude.getInstance().identify(identify);
+};
+
+// wrapper for testing purposes
+Amplitude.prototype.getReferrer = function() {
+  return document.referrer;
+};
+
 function mapRevenueAttributes(track) {
   // Revenue type can be anything such as Refund, Tax, etc.
   // Using mapper here to support future ecomm event => revenue mappings (Order Refund, etc.)

integrations/amplitude/test/index.test.js

@@ -254,6 +254,33 @@ describe('Amplitude', function() {
         analytics.identify('id');
         analytics.called(window.amplitude.getInstance().setDeviceId, 'example');
       });
+
+      it('should send referrer if "trackReferrer" is set', function() {
+        var spy = sinon.spy(window.amplitude.getInstance(), 'identify');
+
+        var stub = sinon.stub(amplitude, 'getReferrer');
+        stub.returns('http://examplepage.com/');
+
+        amplitude.options.trackReferrer = true;
+
+        analytics.page();
+
+        sinon.assert.calledWith(
+          spy,
+          sinon.match({
+            userPropertiesOperations: sinon.match({
+              $setOnce: sinon.match({
+                initial_referrer: 'http://examplepage.com/',
+                initial_referring_domain: 'examplepage.com'
+              }),
+              $set: sinon.match({
+                referrer: 'http://examplepage.com/',
+                referring_domain: 'examplepage.com'
+              })
+            })
+          })
+        );
+      });
     });
 
     describe('#identify', function() {