feat: Treat self referrals as direct

src/__tests__/posthog-core.test.ts

@@ -4,6 +4,7 @@ import { uuidv7 } from '../uuidv7'
 
 const mockReferrerGetter = jest.fn()
 const mockURLGetter = jest.fn()
+const mockHostGetter = jest.fn()
 jest.mock('../utils/globals', () => {
     const orig = jest.requireActual('../utils/globals')
     return {
@@ -22,6 +23,7 @@ jest.mock('../utils/globals', () => {
             const url = mockURLGetter?.()
             return {
                 href: url,
+                host: mockHostGetter?.(),
                 toString: () => url,
             }
         },
@@ -207,6 +209,27 @@ describe('posthog core', () => {
                 expect(properties['$referrer']).toBe('$direct')
                 expect(properties['$referring_domain']).toBe('$direct')
             })
+
+            it('should use $direct when the referrer is the same as the current host', () => {
+                // arrange
+                const token = uuidv7()
+                mockReferrerGetter.mockReturnValue('https://tracked.example.com')
+                mockHostGetter.mockReturnValue('tracked.example.com')
+                const { posthog, onCapture } = setup({
+                    token,
+                    persistence_name: token,
+                })
+
+                // act
+                posthog.capture(eventName, eventProperties)
+
+                // assert
+                const { $set_once, properties } = onCapture.mock.calls[0][1]
+                expect($set_once['$initial_referrer']).toBe('$direct')
+                expect($set_once['$initial_referring_domain']).toBe('$direct')
+                expect(properties['$referrer']).toBe('$direct')
+                expect(properties['$referring_domain']).toBe('$direct')
+            })
         })
     })
 })

src/utils/event-utils.ts

@@ -126,22 +126,27 @@ export const Info = {
 
     deviceType: detectDeviceType,
 
-    referrer: function (): string {
-        return document?.referrer || '$direct'
+    referrerInfo: function (): Record<string, any> {
+        const referrer = document?.referrer
+        const referring_domain = referrer ? convertToURL(referrer)?.host : undefined
+        if (!referrer || !referring_domain || referring_domain === location?.host) {
+            return {
+                $referrer: '$direct',
+                $referring_domain: '$direct',
+            }
+        }
+        return {
+            $referrer: referrer,
+            $referring_domain: referring_domain,
+        }
     },
 
-    referringDomain: function (): string {
-        if (!document?.referrer) {
-            return '$direct'
-        }
-        return convertToURL(document.referrer)?.host || '$direct'
+    referrer: function (): string {
+        return this.referrerInfo().$referrer
     },
 
-    referrerInfo: function (): Record<string, any> {
-        return {
-            $referrer: this.referrer(),
-            $referring_domain: this.referringDomain(),
-        }
+    referringDomain: function (): string {
+        return this.referrerInfo().$referring_domain
     },
 
     initialPersonInfo: function (): Record<string, any> {