Update to look for datalayer of gtag script

Author: dwyfrequency

packages/analytics/src/helpers.test.ts

@@ -57,9 +57,10 @@ describe('Gtag wrapping functions', () => {
   });
 
   it('insertScriptIfNeeded inserts script tag', () => {
-    expect(findGtagScriptOnPage()).to.be.null;
-    insertScriptTag('customDataLayerName', fakeMeasurementId);
-    const scriptTag = findGtagScriptOnPage();
+    const customDataLayerName = 'customDataLayerName';
+    expect(findGtagScriptOnPage(customDataLayerName)).to.be.null;
+    insertScriptTag(customDataLayerName, fakeMeasurementId);
+    const scriptTag = findGtagScriptOnPage(customDataLayerName);
     expect(scriptTag).to.not.be.null;
     expect(scriptTag!.src).to.contain(`l=customDataLayerName`);
     expect(scriptTag!.src).to.contain(`id=${fakeMeasurementId}`);

packages/analytics/src/helpers.ts

@@ -320,10 +320,20 @@ export function wrapOrCreateGtag(
 /**
  * Returns first script tag in DOM matching our gtag url pattern.
  */
-export function findGtagScriptOnPage(): HTMLScriptElement | null {
+// TODO: We'll have this take a datalayer name
+// We'll check if a script exists and if it has the same data layer name
+export function findGtagScriptOnPage(
+  dataLayerName: string
+): HTMLScriptElement | null {
+  console.log(findGtagScriptOnPage);
+  console.log(dataLayerName);
   const scriptTags = window.document.getElementsByTagName('script');
   for (const tag of Object.values(scriptTags)) {
-    if (tag.src && tag.src.includes(GTAG_URL)) {
+    if (
+      tag.src &&
+      tag.src.includes(GTAG_URL) &&
+      tag.src.includes(dataLayerName)
+    ) {
       return tag;
     }
   }

packages/analytics/src/index.test.ts

@@ -349,7 +349,7 @@ describe('FirebaseAnalytics instance tests', () => {
       // Successfully resolves fake IDB open request.
       fakeRequest.onsuccess();
       await initializationPromisesMap[fakeAppParams.appId];
-      expect(findGtagScriptOnPage()).to.not.be.null;
+      expect(findGtagScriptOnPage('dataLayer')).to.not.be.null;
       expect(typeof window['gtag']).to.equal('function');
       expect(Array.isArray(window['dataLayer'])).to.be.true;
 

packages/analytics/src/initialize-analytics.ts

@@ -119,8 +119,9 @@ export async function _initializeAnalytics(
     fidPromise
   ]);
 
-  // Detect if user has already put the gtag <script> tag on this page.
-  if (!findGtagScriptOnPage()) {
+  // Detect if user has already put the gtag <script> tag on this page with the passed in
+  // data layer name.
+  if (!findGtagScriptOnPage(dataLayerName)) {
     insertScriptTag(dataLayerName, dynamicConfig.measurementId);
   }