fix: Don't use session storage in memory mode

src/__tests__/posthog-persistence.test.ts

@@ -3,6 +3,9 @@ import { PostHogPersistence } from '../posthog-persistence'
 import { SESSION_ID, USER_STATE } from '../constants'
 import { PostHogConfig } from '../types'
 import Mock = jest.Mock
+import { PostHog } from '../posthog-core'
+import { window } from '../utils/globals'
+import { uuidv7 } from '../uuidv7'
 
 let referrer = '' // No referrer by default
 Object.defineProperty(document, 'referrer', { get: () => referrer })
@@ -203,4 +206,45 @@ describe('persistence', () => {
             expect(lib.properties()).toEqual(expectedProps())
         })
     })
+
+    describe('posthog', () => {
+        it('should not store anything in localstorage, or cookies when in sessionStorage mode', () => {
+            const token = uuidv7()
+            const persistenceKey = `ph_${token}_posthog`
+            const posthog = new PostHog().init(token, {
+                persistence: 'sessionStorage',
+            })
+            posthog.register({ distinct_id: 'test', test_prop: 'test_val' })
+            posthog.capture('test_event')
+            expect(window.localStorage.getItem(persistenceKey)).toEqual(null)
+            expect(document.cookie).toEqual('')
+            expect(window.sessionStorage.getItem(persistenceKey)).toBeTruthy()
+        })
+
+        it('should not store anything in localstorage, sessionstorage, or cookies when in memory mode', () => {
+            const token = uuidv7()
+            const persistenceKey = `ph_${token}_posthog`
+            const posthog = new PostHog().init(token, {
+                persistence: 'memory',
+            })
+            posthog.register({ distinct_id: 'test', test_prop: 'test_val' })
+            posthog.capture('test_event')
+            expect(window.localStorage.getItem(persistenceKey)).toEqual(null)
+            expect(window.sessionStorage.getItem(persistenceKey)).toEqual(null)
+            expect(document.cookie).toEqual('')
+        })
+
+        it('should not store anything in cookies when in localstorage mode', () => {
+            const token = uuidv7()
+            const persistenceKey = `ph_${token}_posthog`
+            const posthog = new PostHog().init(token, {
+                persistence: 'localStorage',
+            })
+            posthog.register({ distinct_id: 'test', test_prop: 'test_val' })
+            posthog.capture('test_event')
+            expect(window.localStorage.getItem(persistenceKey)).toBeTruthy()
+            expect(window.sessionStorage.getItem(persistenceKey)).toBeTruthy()
+            expect(document.cookie).toEqual('')
+        })
+    })
 })

src/posthog-core.ts

@@ -412,7 +412,7 @@ export class PostHog {
 
         this.persistence = new PostHogPersistence(this.config)
         this.sessionPersistence =
-            this.config.persistence === 'sessionStorage'
+            this.config.persistence === 'sessionStorage' || this.config.persistence === 'memory'
                 ? this.persistence
                 : new PostHogPersistence({ ...this.config, persistence: 'sessionStorage' })
 
@@ -1786,7 +1786,7 @@ export class PostHog {
 
             this.persistence?.update_config(this.config, oldConfig)
             this.sessionPersistence =
-                this.config.persistence === 'sessionStorage'
+                this.config.persistence === 'sessionStorage' || this.config.persistence === 'memory'
                     ? this.persistence
                     : new PostHogPersistence({ ...this.config, persistence: 'sessionStorage' })