From 0fead1125a70dfc2f46c4710b626f599b8117e84 Mon Sep 17 00:00:00 2001
From: tyiuhc <tim.yiu@amplitude.com>
Date: Thu, 9 Jan 2025 13:41:18 -0800
Subject: [PATCH 1/4] fix: migrate to use web_exp_id for web experiment
 device_id bucketing

---
 packages/experiment-tag/src/experiment.ts | 30 ++++++++++-------------
 1 file changed, 13 insertions(+), 17 deletions(-)

diff --git a/packages/experiment-tag/src/experiment.ts b/packages/experiment-tag/src/experiment.ts
index dcc3e370..fe05c3e9 100644
--- a/packages/experiment-tag/src/experiment.ts
+++ b/packages/experiment-tag/src/experiment.ts
@@ -59,24 +59,20 @@ export const initializeExperiment = async (
     user = {};
   }
 
-  // create new user if it does not exist, or it does not have device_id or web_exp_id
-  if (Object.keys(user).length === 0 || !user.device_id || !user.web_exp_id) {
-    if (!user.device_id || !user.web_exp_id) {
-      // if user has device_id, migrate it to web_exp_id
-      if (user.device_id) {
-        user.web_exp_id = user.device_id;
-      } else if (user.web_exp_id) {
-        user.device_id = user.web_exp_id;
-      } else {
-        const uuid = UUID();
-        // both IDs are set for backwards compatibility, to be removed in future update
-        user = { device_id: uuid, web_exp_id: uuid };
-      }
-      globalScope.localStorage.setItem(
-        experimentStorageName,
-        JSON.stringify(user),
-      );
+  // create new user if it does not exist, or it does not have web_exp_id
+  if (Object.keys(user).length === 0 || !user.web_exp_id) {
+    // if user has device_id, migrate it to web_exp_id
+    if (user.device_id) {
+      user.web_exp_id = user.device_id;
+      delete user.device_id;
+    } else {
+      const uuid = UUID();
+      user = { web_exp_id: uuid };
     }
+    globalScope.localStorage.setItem(
+      experimentStorageName,
+      JSON.stringify(user),
+    );
   }
 
   const urlParams = getUrlParams();

From bcee1efa6e521a27b0b8fe16f39f5a8c15fe7ecf Mon Sep 17 00:00:00 2001
From: tyiuhc <tim.yiu@amplitude.com>
Date: Thu, 9 Jan 2025 14:23:21 -0800
Subject: [PATCH 2/4] refactor web_exp_id logic

---
 packages/experiment-tag/src/experiment.ts | 22 ++++++++++++----------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/packages/experiment-tag/src/experiment.ts b/packages/experiment-tag/src/experiment.ts
index fe05c3e9..dfe2b305 100644
--- a/packages/experiment-tag/src/experiment.ts
+++ b/packages/experiment-tag/src/experiment.ts
@@ -59,16 +59,18 @@ export const initializeExperiment = async (
     user = {};
   }
 
-  // create new user if it does not exist, or it does not have web_exp_id
-  if (Object.keys(user).length === 0 || !user.web_exp_id) {
-    // if user has device_id, migrate it to web_exp_id
-    if (user.device_id) {
-      user.web_exp_id = user.device_id;
-      delete user.device_id;
-    } else {
-      const uuid = UUID();
-      user = { web_exp_id: uuid };
-    }
+  // migrate device_id to web_exp_id if it exists
+  // if web_exp_id does not exist, create a new one
+  // if both web_exp_id and device_id exist, remove device_id
+  if (!user.web_exp_id) {
+    user.web_exp_id = user.device_id || UUID();
+    delete user.device_id;
+    globalScope.localStorage.setItem(
+      experimentStorageName,
+      JSON.stringify(user),
+    );
+  } else if (user.web_exp_id && user.device_id) {
+    delete user.device_id;
     globalScope.localStorage.setItem(
       experimentStorageName,
       JSON.stringify(user),

From ccb1914ab1305cc3d6ce3b12e82ab8c5e24cde17 Mon Sep 17 00:00:00 2001
From: tyiuhc <tim.yiu@amplitude.com>
Date: Thu, 9 Jan 2025 14:51:48 -0800
Subject: [PATCH 3/4] fix tests

---
 packages/experiment-tag/test/experiment.test.ts | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/experiment-tag/test/experiment.test.ts b/packages/experiment-tag/test/experiment.test.ts
index 4838e524..71fec36a 100644
--- a/packages/experiment-tag/test/experiment.test.ts
+++ b/packages/experiment-tag/test/experiment.test.ts
@@ -55,12 +55,11 @@ describe('initializeExperiment', () => {
   test('should initialize experiment with empty user', () => {
     initializeExperiment(stringify(apiKey), JSON.stringify([]));
     expect(ExperimentClient.prototype.setUser).toHaveBeenCalledWith({
-      device_id: 'mock',
       web_exp_id: 'mock',
     });
     expect(mockGlobal.localStorage.setItem).toHaveBeenCalledWith(
       'EXP_1',
-      JSON.stringify({ device_id: 'mock', web_exp_id: 'mock' }),
+      JSON.stringify({ web_exp_id: 'mock' }),
     );
   });
 

From 612ce2617a157b597d4476ba67bb7cb59c37532e Mon Sep 17 00:00:00 2001
From: tyiuhc <tim.yiu@amplitude.com>
Date: Thu, 9 Jan 2025 18:24:30 -0800
Subject: [PATCH 4/4] nit: fix comment

---
 packages/experiment-tag/src/experiment.ts | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/packages/experiment-tag/src/experiment.ts b/packages/experiment-tag/src/experiment.ts
index dfe2b305..6a1bcfe8 100644
--- a/packages/experiment-tag/src/experiment.ts
+++ b/packages/experiment-tag/src/experiment.ts
@@ -59,9 +59,10 @@ export const initializeExperiment = async (
     user = {};
   }
 
-  // migrate device_id to web_exp_id if it exists
-  // if web_exp_id does not exist, create a new one
-  // if both web_exp_id and device_id exist, remove device_id
+  // if web_exp_id does not exist:
+  // 1. if device_id exists, migrate device_id to web_exp_id and remove device_id
+  // 2. if device_id does not exist, create a new web_exp_id
+  // 3. if both device_id and web_exp_id exist, remove device_id
   if (!user.web_exp_id) {
     user.web_exp_id = user.device_id || UUID();
     delete user.device_id;