From c29e869f3dd51dbe96120eec2940f70f8c683893 Mon Sep 17 00:00:00 2001
From: wo-o29 <woogur29@gmail.com>
Date: Sat, 13 Sep 2025 15:46:11 +0900
Subject: [PATCH 1/4] refactor: remove undefined from usePrevious compare
 function and return type

---
 src/hooks/usePrevious/usePrevious.ts | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/src/hooks/usePrevious/usePrevious.ts b/src/hooks/usePrevious/usePrevious.ts
index 8ddf60dd..2ae4eb97 100644
--- a/src/hooks/usePrevious/usePrevious.ts
+++ b/src/hooks/usePrevious/usePrevious.ts
@@ -1,6 +1,6 @@
 import { useRef } from 'react';
 
-const strictEquals = <T>(prev: T | undefined, next: T) => prev === next;
+const strictEquals = <T>(prev: T, next: T) => prev === next;
 
 /**
  * @description
@@ -11,9 +11,9 @@ const strictEquals = <T>(prev: T | undefined, next: T) => prev === next;
  *
  * @template T - The type of the state.
  * @param {T} state - The state whose previous value is to be tracked.
- * @param {(prev: T | undefined, next: T) => boolean} [compare] - An optional comparison function to determine if the state has changed.
+ * @param {(prev: T, next: T) => boolean} [compare] - An optional comparison function to determine if the state has changed.
  *
- * @returns {T | undefined} The previous value of the state.
+ * @returns {T} The previous value of the state.
  *
  * @example
  * const [count, setCount] = useState(0);

From 57bbf080deaedfe798815b48dd0d1e8a1bb5f96c Mon Sep 17 00:00:00 2001
From: wo-o29 <woogur29@gmail.com>
Date: Sat, 13 Sep 2025 15:46:14 +0900
Subject: [PATCH 2/4] docs: remove undefined from usePrevious compare function
 and return type

---
 src/hooks/usePrevious/ko/usePrevious.md | 8 ++++----
 src/hooks/usePrevious/usePrevious.md    | 8 ++++----
 2 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/src/hooks/usePrevious/ko/usePrevious.md b/src/hooks/usePrevious/ko/usePrevious.md
index b924fd37..f1d9a623 100644
--- a/src/hooks/usePrevious/ko/usePrevious.md
+++ b/src/hooks/usePrevious/ko/usePrevious.md
@@ -7,8 +7,8 @@
 ```ts
 function usePrevious<T>(
   state: T,
-  compare: (prev: T | undefined, next: T) => boolean
-): T | undefined;
+  compare: (prev: T, next: T) => boolean
+): T;
 ```
 
 ### 파라미터
@@ -22,7 +22,7 @@ function usePrevious<T>(
 
 <Interface
   name="compare"
-  type="(prev: T | undefined, next: T) => boolean"
+  type="(prev: T, next: T) => boolean"
   description="상태가 변경되었는지를 판단하기 위한 선택적 비교 함수예요."
 />
 
@@ -30,7 +30,7 @@ function usePrevious<T>(
 
 <Interface
   name=""
-  type="T | undefined"
+  type="T"
   description="상태의 이전 값이에요."
 />
 
diff --git a/src/hooks/usePrevious/usePrevious.md b/src/hooks/usePrevious/usePrevious.md
index 7c461e2e..943aaf9d 100644
--- a/src/hooks/usePrevious/usePrevious.md
+++ b/src/hooks/usePrevious/usePrevious.md
@@ -7,8 +7,8 @@
 ```ts
 function usePrevious<T>(
   state: T,
-  compare: (prev: T | undefined, next: T) => boolean
-): T | undefined;
+  compare: (prev: T, next: T) => boolean
+): T;
 ```
 
 ### Parameters
@@ -22,7 +22,7 @@ function usePrevious<T>(
 
 <Interface
   name="compare"
-  type="(prev: T | undefined, next: T) => boolean"
+  type="(prev: T, next: T) => boolean"
   description="An optional comparison function to determine if the state has changed."
 />
 
@@ -30,7 +30,7 @@ function usePrevious<T>(
 
 <Interface
   name=""
-  type="T | undefined"
+  type="T"
   description="previous value of the state."
 />
 

From d9aabf12849c67bafcbfe5429e591f5828ae7ef2 Mon Sep 17 00:00:00 2001
From: wo-o29 <woogur29@gmail.com>
Date: Sat, 21 Feb 2026 22:05:10 +0900
Subject: [PATCH 3/4] fix: document format

---
 packages/core/src/hooks/usePrevious/ko/usePrevious.md | 5 +----
 packages/core/src/hooks/usePrevious/usePrevious.md    | 5 +----
 2 files changed, 2 insertions(+), 8 deletions(-)

diff --git a/packages/core/src/hooks/usePrevious/ko/usePrevious.md b/packages/core/src/hooks/usePrevious/ko/usePrevious.md
index f1d9a623..a778ce46 100644
--- a/packages/core/src/hooks/usePrevious/ko/usePrevious.md
+++ b/packages/core/src/hooks/usePrevious/ko/usePrevious.md
@@ -5,10 +5,7 @@
 ## 인터페이스
 
 ```ts
-function usePrevious<T>(
-  state: T,
-  compare: (prev: T, next: T) => boolean
-): T;
+function usePrevious<T>(state: T, compare: (prev: T, next: T) => boolean): T;
 ```
 
 ### 파라미터
diff --git a/packages/core/src/hooks/usePrevious/usePrevious.md b/packages/core/src/hooks/usePrevious/usePrevious.md
index 943aaf9d..7c480a7f 100644
--- a/packages/core/src/hooks/usePrevious/usePrevious.md
+++ b/packages/core/src/hooks/usePrevious/usePrevious.md
@@ -5,10 +5,7 @@
 ## Interface
 
 ```ts
-function usePrevious<T>(
-  state: T,
-  compare: (prev: T, next: T) => boolean
-): T;
+function usePrevious<T>(state: T, compare: (prev: T, next: T) => boolean): T;
 ```
 
 ### Parameters

From ca35cc722b911c33892dfebbff852a70db9f0766 Mon Sep 17 00:00:00 2001
From: kimyouknow <kimyouknow@toss.im>
Date: Tue, 7 Apr 2026 21:40:01 +0900
Subject: [PATCH 4/4] chore: add changeset for usePrevious type improvement

---
 .changeset/refactor-useprevious-type.md | 5 +++++
 1 file changed, 5 insertions(+)
 create mode 100644 .changeset/refactor-useprevious-type.md

diff --git a/.changeset/refactor-useprevious-type.md b/.changeset/refactor-useprevious-type.md
new file mode 100644
index 00000000..86afb9bd
--- /dev/null
+++ b/.changeset/refactor-useprevious-type.md
@@ -0,0 +1,5 @@
+---
+'react-simplikit': patch
+---
+
+refactor(usePrevious): remove unnecessary `undefined` from compare argument and return type