Load Modules support initialization

Rather than obscurely loading instrumentation code as a side
effect of loading UI code, run it explicitly inside the index.js
initalization code. Instrumentation is moved to its own file
and Popups modules now support an init function.

Change-Id: I9d2643ec8fb4e1dedc7ab9534b2965272f12335f

src/index.js

@@ -29,6 +29,7 @@ import { previewTypes, getPreviewType,
 import isReferencePreviewsEnabled from './isReferencePreviewsEnabled';
 import setUserConfigFlags from './setUserConfigFlags';
 import { registerGatewayForPreviewType, getGatewayForPreviewType } from './gateway';
+import { initReferencePreviewsInstrumentation } from './instrumentation/referencePreviews';
 
 const EXCLUDED_LINK_SELECTORS = [
 	'.extiw',
@@ -236,7 +237,10 @@ function handleDOMEventIfEligible( handler ) {
 			type: previewTypes.TYPE_REFERENCE,
 			selector: '#mw-content-text .reference a[ href*="#" ]',
 			gateway: referenceGateway,
-			renderFn: createReferencePreview
+			renderFn: createReferencePreview,
+			init: () => {
+				initReferencePreviewsInstrumentation();
+			}
 		} );
 	}
 	if ( !isAnythingEligible() ) {

src/instrumentation/referencePreviews.js

@@ -0,0 +1,21 @@
+let isTracking = false;
+
+export const LOGGING_SCHEMA = 'event.ReferencePreviewsPopups';
+
+/**
+ * Run once the preview is initialized.
+ */
+export function initReferencePreviewsInstrumentation() {
+	if ( mw.config.get( 'wgPopupsReferencePreviews' ) &&
+		navigator.sendBeacon &&
+		mw.config.get( 'wgIsArticle' ) &&
+		!isTracking
+	) {
+		isTracking = true;
+		mw.track( LOGGING_SCHEMA, { action: 'pageview' } );
+	}
+}
+
+export function isTrackingEnabled() {
+	return isTracking;
+}

src/integrations/mwpopups.js

@@ -57,7 +57,7 @@ export default function createMwPopups( store, registerModel, registerPreviewUI,
 		 * @param {PopupModule} module
 		 */
 		register: function ( module ) {
-			const { type, selector, gateway, renderFn, subTypes } = module;
+			const { type, selector, gateway, renderFn, subTypes, init } = module;
 			if ( !type || !selector || !gateway ) {
 				throw new Error(
 					`Registration of Popups custom preview type "${type}" failed: You must specify a type, a selector, and a gateway.`
@@ -71,6 +71,10 @@ export default function createMwPopups( store, registerModel, registerPreviewUI,
 					registerPreviewUI( subTypePreview.type, subTypePreview.renderFn );
 				} );
 			}
+			// Run initialization function if provided.
+			if ( typeof init === 'function' ) {
+				init();
+			}
 		}
 	};
 }

src/ui/templates/referencePreview/referencePreview.js

@@ -1,7 +1,7 @@
 /**
  * @module referencePreview
  */
-
+import { isTrackingEnabled, LOGGING_SCHEMA } from '../../../instrumentation/referencePreviews';
 import { renderPopup } from '../popup/popup';
 import { createNodeFromTemplate, escapeHTML } from '../templateUtil';
 
@@ -22,19 +22,6 @@ const templateHTML = `
 	</footer>
 </div>`;
 
-const LOGGING_SCHEMA = 'event.ReferencePreviewsPopups';
-let isTracking = false;
-$( () => {
-	if ( mw.config.get( 'wgPopupsReferencePreviews' ) &&
-		navigator.sendBeacon &&
-		mw.config.get( 'wgIsArticle' ) &&
-		!isTracking
-	) {
-		isTracking = true;
-		mw.track( LOGGING_SCHEMA, { action: 'pageview' } );
-	}
-} );
-
 /**
  * @param {ext.popups.ReferencePreviewModel} model
  * @return {JQuery}
@@ -108,7 +95,7 @@ export function renderReferencePreview(
 		$el.find( '.mwe-popups-container' ).addClass( 'footer-empty' );
 	}
 
-	if ( isTracking ) {
+	if ( isTrackingEnabled() ) {
 		$el.find( '.mw-parser-output' ).on( 'click', 'a', () => {
 			mw.track( LOGGING_SCHEMA, {
 				action: 'clickedReferencePreviewsContentLink'
@@ -121,7 +108,7 @@ export function renderReferencePreview(
 			// We are dealing with floating point numbers here when the page is zoomed!
 			scrolledToBottom = element.scrollTop >= element.scrollHeight - element.clientHeight - 1;
 
-		if ( isTracking ) {
+		if ( isTrackingEnabled() ) {
 			if ( !element.isOpenRecorded ) {
 				mw.track( LOGGING_SCHEMA, {
 					action: 'poppedOpen',