feat: support latest referrer (#9)

Co-authored-by: xiaoweii <xiaoweii@amazom.com>

Author: zhu-xiaowei

src/browser/BrowserInfo.ts

@@ -1,3 +1,5 @@
+import { Logger } from '@aws-amplify/core';
+
 /**
  *  Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
  *
@@ -10,6 +12,7 @@
  *  OR CONDITIONS OF ANY KIND, express or implied. See the License for the specific language governing permissions
  *  and limitations under the License.
  */
+const logger = new Logger('BrowserInfo');
 
 export class BrowserInfo {
 	locale: string;
@@ -19,6 +22,8 @@ export class BrowserInfo {
 	userAgent: string;
 	zoneOffset: number;
 	hostName: string;
+	latestReferrer: string;
+	latestReferrerHost: string;
 
 	constructor() {
 		if (!BrowserInfo.isBrowser()) return;
@@ -29,6 +34,15 @@ export class BrowserInfo {
 		this.userAgent = userAgent;
 		this.zoneOffset = -new Date().getTimezoneOffset() * 60000;
 		this.hostName = window.location.hostname;
+		this.latestReferrer = window.document.referrer;
+		if (this.latestReferrer && this.latestReferrer !== '') {
+			try {
+				const url = new URL(this.latestReferrer);
+				this.latestReferrerHost = url.host;
+			} catch (error) {
+				logger.warn('parse latest referrer domain failed: ' + error);
+			}
+		}
 	}
 
 	initLocalInfo(locale: string) {

src/provider/AnalyticsEventBuilder.ts

@@ -50,6 +50,10 @@ export class AnalyticsEventBuilder {
 			BrowserInfo.getCurrentPageTitle();
 		attributes[Event.ReservedAttribute.PAGE_URL] =
 			BrowserInfo.getCurrentPageUrl();
+		attributes[Event.ReservedAttribute.LATEST_REFERRER] =
+			browserInfo.latestReferrer;
+		attributes[Event.ReservedAttribute.LATEST_REFERRER_HOST] =
+			browserInfo.latestReferrerHost;
 
 		const items = this.getEventItemsWithCheck(event.items, attributes);
 

src/provider/Event.ts

@@ -51,6 +51,8 @@ export class Event {
 		PAGE_TITLE: '_page_title',
 		PAGE_REFERRER: '_page_referrer',
 		PAGE_REFERRER_TITLE: '_page_referrer_title',
+		LATEST_REFERRER: '_latest_referrer',
+		LATEST_REFERRER_HOST: '_latest_referrer_host',
 		ENTRANCES: '_entrances',
 		SESSION_ID: '_session_id',
 		SESSION_DURATION: '_session_duration',

test/browser/BrowserInfo.test.ts

@@ -14,13 +14,20 @@ import { BrowserInfo } from '../../src/browser';
 
 describe('BrowserInfo test', () => {
 	test('test create BrowserInfo', () => {
+		const referrer = 'https://example.com/collect';
+		Object.defineProperty(window.document, 'referrer', {
+			writable: true,
+			value: referrer,
+		});
 		const browserInfo = new BrowserInfo();
 		expect(browserInfo.userAgent.length > 0).toBeTruthy();
 		expect(browserInfo.hostName.length > 0).toBeTruthy();
 		expect(browserInfo.locale.length > 0).toBeTruthy();
 		expect(browserInfo.system_language.length > 0).toBeTruthy();
 		expect(browserInfo.zoneOffset).not.toBeUndefined();
 		expect(browserInfo.make.length > 0).toBeTruthy();
+		expect(browserInfo.latestReferrer).toBe(referrer);
+		expect(browserInfo.latestReferrerHost).toBe('example.com');
 	});
 
 	test('test init locale', () => {

test/provider/AnalyticsEventBuilder.test.ts

@@ -23,6 +23,11 @@ import { ClickstreamAttribute, Item } from '../../src/types';
 
 describe('AnalyticsEventBuilder test', () => {
 	test('test create event with common attributes', async () => {
+		const referrer = 'https://example1.com/collect';
+		Object.defineProperty(window.document, 'referrer', {
+			writable: true,
+			value: referrer,
+		});
 		const context = new ClickstreamContext(new BrowserInfo(), {
 			appId: 'testApp',
 			endpoint: 'https://example.com/collect',
@@ -56,6 +61,8 @@ describe('AnalyticsEventBuilder test', () => {
 		expect(Event.ReservedAttribute.SESSION_DURATION in event.attributes);
 		expect(Event.ReservedAttribute.SESSION_NUMBER in event.attributes);
 		expect(Event.ReservedAttribute.SESSION_START_TIMESTAMP in event.attributes);
+		expect(Event.ReservedAttribute.LATEST_REFERRER in event.attributes);
+		expect(Event.ReservedAttribute.LATEST_REFERRER_HOST in event.attributes);
 	});
 
 	test('test check event attribute reached max attribute number limit', () => {