Created function to create policy

Author: dwyfrequency

packages/analytics/src/helpers.test.ts

@@ -25,7 +25,8 @@ import {
   wrapOrCreateGtag,
   findGtagScriptOnPage,
   promiseAllSettled,
-  createGtagTrustedTypesScriptURL
+  createGtagTrustedTypesScriptURL,
+  createTrustedTypesPolicy
 } from './helpers';
 import { GtagCommand, GTAG_URL } from './constants';
 import { Deferred } from '@firebase/util';
@@ -48,30 +49,63 @@ const fakeDynamicConfig: DynamicConfig = {
 const fakeDynamicConfigPromises = [Promise.resolve(fakeDynamicConfig)];
 
 describe('Trusted Types policies and functions', () => {
-  const ttStub = stub(
-    window.trustedTypes as TrustedTypePolicyFactory,
-    'createPolicy'
-  ).returns({
-    createScriptURL: (s: string) => s
-  } as any);
-
-  it('Verify trustedTypes is called if the API is available', () => {
-    expect(ttStub).to.be.called;
-  });
+  describe('Trusted types exists', () => {
+    let ttStub: SinonStub;
+
+    beforeEach(() => {
+      ttStub = stub(
+        window.trustedTypes as TrustedTypePolicyFactory,
+        'createPolicy'
+      ).returns({
+        createScriptURL: (s: string) => s
+      } as any);
+    });
+
+    afterEach(() => {
+      removeGtagScripts();
+      ttStub.restore();
+    });
+
+    it('Verify trustedTypes is called if the API is available', () => {
+      const trustedTypesPolicy = createTrustedTypesPolicy(
+        'firebase-js-sdk-policy',
+        {
+          createScriptURL: createGtagTrustedTypesScriptURL
+        }
+      );
 
-  it('createGtagTrustedTypesScriptURL verifies gtag URL base exists when a URL is provided', () => {
-    expect(createGtagTrustedTypesScriptURL(GTAG_URL)).to.equal(GTAG_URL);
+      expect(ttStub).to.be.called;
+      expect(trustedTypesPolicy).not.to.be.undefined;
+    });
+
+    it('createGtagTrustedTypesScriptURL verifies gtag URL base exists when a URL is provided', () => {
+      expect(createGtagTrustedTypesScriptURL(GTAG_URL)).to.equal(GTAG_URL);
+    });
+
+    it('createGtagTrustedTypesScriptURL rejects URLs with non-gtag base', () => {
+      const NON_GTAG_URL = 'http://iamnotgtag.com';
+      const consoleErrorStub = stub(console, 'error');
+
+      expect(createGtagTrustedTypesScriptURL(NON_GTAG_URL)).to.equal('');
+      expect(consoleErrorStub).to.be.calledWith(
+        'Unknown gtag resource!',
+        NON_GTAG_URL
+      );
+    });
   });
 
-  it('createGtagTrustedTypesScriptURL rejects URLs with non-gtag base', () => {
-    const NON_GTAG_URL = 'http://iamnotgtag.com';
-    const consoleErrorStub = stub(console, 'error');
+  describe('Trusted types does not exist', () => {
+    it('Verify trustedTypes functions are not called if the API is not available', () => {
+      delete window.trustedTypes;
+      const trustedTypesPolicy = createTrustedTypesPolicy(
+        'firebase-js-sdk-policy',
+        {
+          createScriptURL: createGtagTrustedTypesScriptURL
+        }
+      );
 
-    expect(createGtagTrustedTypesScriptURL(NON_GTAG_URL)).to.equal('');
-    expect(consoleErrorStub).to.be.calledWith(
-      'Unknown gtag resource!',
-      NON_GTAG_URL
-    );
+      expect(trustedTypesPolicy).to.be.undefined;
+    });
   });
 });
 

packages/analytics/src/helpers.ts

@@ -29,15 +29,6 @@ import { AnalyticsError, ERROR_FACTORY } from './errors';
 // Possible parameter types for gtag 'event' and 'config' commands
 type GtagConfigOrEventParams = ControlParams & EventParams & CustomParams;
 
-// Create a TrustedTypes policy that we can use for updating src
-// properties
-let _ttPolicy: Partial<TrustedTypePolicy>;
-if (window.trustedTypes) {
-  _ttPolicy = window.trustedTypes.createPolicy('firebase-js-sdk-policy', {
-    createScriptURL: createGtagTrustedTypesScriptURL
-  });
-}
-
 /**
  * Verifies and creates a TrustedScriptURL.
  */
@@ -65,6 +56,30 @@ export function promiseAllSettled<T>(
   return Promise.all(promises.map(promise => promise.catch(e => e)));
 }
 
+/**
+ * Creates a TrustedTypePolicy object that implements the rules passed as policyOptions.
+ *
+ * @param policyName A string containing the name of the policy
+ * @param policyOptions Object containing implementations of instance methods for TrustedTypesPolicy, see {@link https://developer.mozilla.org/en-US/docs/Web/API/TrustedTypePolicy#instance_methods
+ * | the TrustedTypePolicy reference documentation}.
+ * @returns
+ */
+export function createTrustedTypesPolicy(
+  policyName: string,
+  policyOptions: Partial<TrustedTypePolicyOptions>
+): Partial<TrustedTypePolicy> | undefined {
+  // Create a TrustedTypes policy that we can use for updating src
+  // properties
+  let trustedTypesPolicy: Partial<TrustedTypePolicy> | undefined;
+  if (window.trustedTypes) {
+    trustedTypesPolicy = window.trustedTypes.createPolicy(
+      policyName,
+      policyOptions
+    );
+  }
+  return trustedTypesPolicy;
+}
+
 /**
  * Inserts gtag script tag into the page to asynchronously download gtag.
  * @param dataLayerName Name of datalayer (most often the default, "_dataLayer").
@@ -73,13 +88,20 @@ export function insertScriptTag(
   dataLayerName: string,
   measurementId: string
 ): void {
+  const trustedTypesPolicy = createTrustedTypesPolicy(
+    'firebase-js-sdk-policy',
+    {
+      createScriptURL: createGtagTrustedTypesScriptURL
+    }
+  );
+
   const script = document.createElement('script');
   // We are not providing an analyticsId in the URL because it would trigger a `page_view`
   // without fid. We will initialize ga-id using gtag (config) command together with fid.
 
   const gtagScriptURL = `${GTAG_URL}?l=${dataLayerName}&id=${measurementId}`;
-  (script.src as string | TrustedScriptURL) = _ttPolicy
-    ? (_ttPolicy as TrustedTypePolicy)?.createScriptURL(gtagScriptURL)
+  (script.src as string | TrustedScriptURL) = trustedTypesPolicy
+    ? (trustedTypesPolicy as TrustedTypePolicy)?.createScriptURL(gtagScriptURL)
     : gtagScriptURL;
 
   script.async = true;