Also flush on the pagehide event

Author: andrewbrook

packages/telemetry/src/helpers.test.ts

@@ -66,6 +66,7 @@ describe('helpers', () => {
 
   beforeEach(() => {
     emittedLogs = [];
+    flushed = false;
     storage = {};
     // @ts-ignore
     originalSessionStorage = global.sessionStorage;
@@ -154,7 +155,7 @@ describe('helpers', () => {
         registerListeners(fakeTelemetry);
       });
     } else {
-      it('should flush logs when the page is hidden', () => {
+      it('should flush logs when the visibility changes to hidden', () => {
         registerListeners(fakeTelemetry);
 
         expect(flushed).to.be.false;
@@ -167,6 +168,16 @@ describe('helpers', () => {
 
         expect(flushed).to.be.true;
       });
+
+      it('should flush logs when the pagehide event fires', () => {
+        registerListeners(fakeTelemetry);
+
+        expect(flushed).to.be.false;
+
+        window.dispatchEvent(new Event('pagehide'));
+
+        expect(flushed).to.be.true;
+      });
     }
   });
 });

packages/telemetry/src/helpers.ts

@@ -83,7 +83,8 @@ export function startNewSession(telemetry: Telemetry): void {
 }
 
 /**
- * Registers event listeners to flush logs when the page is hidden.
+ * Registers event listeners to flush logs when the page is hidden. In some cases multiple listeners
+ * may trigger at the same time, but flushing only occurs once per batch.
  */
 export function registerListeners(telemetry: Telemetry): void {
   if (typeof window !== 'undefined' && typeof document !== 'undefined') {
@@ -92,6 +93,9 @@ export function registerListeners(telemetry: Telemetry): void {
         await flush(telemetry);
       }
     });
+    window.addEventListener('pagehide', async () => {
+      await flush(telemetry);
+    });
   }
 }