Defer snowplow loading until rest of dom is loaded

- the work being done in snowplow initialization
  was slowing down dom load times and deferring
  it here should speed it up a bit.

app/assets/javascripts/main.js

@@ -37,7 +37,7 @@ import GlFieldErrors from './gl_field_errors';
 import initUserPopovers from './user_popovers';
 import initBroadcastNotifications from './broadcast_notification';
 import initPersistentUserCallouts from './persistent_user_callouts';
-import { initUserTracking } from './tracking';
+import { initUserTracking, initDefaultTrackers } from './tracking';
 import { __ } from './locale';
 
 import 'ee_else_ce/main_ee';
@@ -111,6 +111,7 @@ function deferredInitialisation() {
   initBroadcastNotifications();
   initFrequentItemDropdowns();
   initPersistentUserCallouts();
+  initDefaultTrackers();
 
   if (document.querySelector('.search')) initSearchAutocomplete();
 

app/assets/javascripts/tracking.js

@@ -126,14 +126,18 @@ export function initUserTracking() {
   const opts = { ...DEFAULT_SNOWPLOW_OPTIONS, ...window.snowplowOptions };
   window.snowplow('newTracker', opts.namespace, opts.hostname, opts);
 
+  document.dispatchEvent(new Event('SnowplowInitialized'));
+}
+
+export function initDefaultTrackers() {
+  if (!Tracking.enabled()) return;
+
   window.snowplow('enableActivityTracking', 30, 30);
   window.snowplow('trackPageView'); // must be after enableActivityTracking
 
-  if (opts.formTracking) window.snowplow('enableFormTracking');
-  if (opts.linkClickTracking) window.snowplow('enableLinkClickTracking');
+  if (window.snowplowOptions.formTracking) window.snowplow('enableFormTracking');
+  if (window.snowplowOptions.linkClickTracking) window.snowplow('enableLinkClickTracking');
 
   Tracking.bindDocument();
   Tracking.trackLoadEvents();
-
-  document.dispatchEvent(new Event('SnowplowInitialized'));
 }

changelogs/unreleased/223855-performance-defer-certain-parts-of-setting-up-snowplow-telemetry.yml

+---
+title: Defer (certain) parts of setting up snowplow telemetry
+merge_request: 40299
+author:
+type: performance

spec/frontend/tracking_spec.js

 import { setHTMLFixture } from './helpers/fixtures';
-import Tracking, { initUserTracking } from '~/tracking';
+import Tracking, { initUserTracking, initDefaultTrackers } from '~/tracking';
 
 describe('Tracking', () => {
   let snowplowSpy;
@@ -17,11 +17,6 @@ describe('Tracking', () => {
   });
 
   describe('initUserTracking', () => {
-    beforeEach(() => {
-      bindDocumentSpy = jest.spyOn(Tracking, 'bindDocument').mockImplementation(() => null);
-      trackLoadEventsSpy = jest.spyOn(Tracking, 'trackLoadEvents').mockImplementation(() => null);
-    });
-
     it('calls through to get a new tracker with the expected options', () => {
       initUserTracking();
       expect(snowplowSpy).toHaveBeenCalledWith('newTracker', '_namespace_', 'app.gitfoo.com', {
@@ -38,9 +33,16 @@ describe('Tracking', () => {
         linkClickTracking: false,
       });
     });
+  });
+
+  describe('initDefaultTrackers', () => {
+    beforeEach(() => {
+      bindDocumentSpy = jest.spyOn(Tracking, 'bindDocument').mockImplementation(() => null);
+      trackLoadEventsSpy = jest.spyOn(Tracking, 'trackLoadEvents').mockImplementation(() => null);
+    });
 
     it('should activate features based on what has been enabled', () => {
-      initUserTracking();
+      initDefaultTrackers();
       expect(snowplowSpy).toHaveBeenCalledWith('enableActivityTracking', 30, 30);
       expect(snowplowSpy).toHaveBeenCalledWith('trackPageView');
       expect(snowplowSpy).not.toHaveBeenCalledWith('enableFormTracking');
@@ -52,18 +54,18 @@ describe('Tracking', () => {
         linkClickTracking: true,
       };
 
-      initUserTracking();
+      initDefaultTrackers();
       expect(snowplowSpy).toHaveBeenCalledWith('enableFormTracking');
       expect(snowplowSpy).toHaveBeenCalledWith('enableLinkClickTracking');
     });
 
     it('binds the document event handling', () => {
-      initUserTracking();
+      initDefaultTrackers();
       expect(bindDocumentSpy).toHaveBeenCalled();
     });
 
     it('tracks page loaded events', () => {
-      initUserTracking();
+      initDefaultTrackers();
       expect(trackLoadEventsSpy).toHaveBeenCalled();
     });
   });