From 6065256b88986b0e754e64dc8251b9b67ef30380 Mon Sep 17 00:00:00 2001
From: Adam C Hamlin <achamlin@gmail.com>
Date: Fri, 12 Jul 2024 23:58:19 -0400
Subject: [PATCH] fix: debounce cancel should clear pending timeout

---
 docs/curry/debounce.mdx      |  2 +-
 src/curry/debounce.ts        | 16 ++++++----------
 tests/curry/debounce.test.ts | 21 +++++++++++++++------
 3 files changed, 22 insertions(+), 17 deletions(-)

diff --git a/docs/curry/debounce.mdx b/docs/curry/debounce.mdx
index e2bd9ddb1..837896dde 100644
--- a/docs/curry/debounce.mdx
+++ b/docs/curry/debounce.mdx
@@ -34,7 +34,7 @@ Source Invocations: - - - - - - - - - - x - - - - - - - - - - - - - - - - - x -
 
 ### Cancel
 
-The function returned by `debounce` has a `cancel` method that when called will permanently stop the source function from being debounced.
+The function returned by `debounce` has a `cancel` method that when called will cancel any pending invocation.
 
 ```ts
 const debounced = _.debounce({ delay: 100 }, api.feed.refresh)
diff --git a/src/curry/debounce.ts b/src/curry/debounce.ts
index a09f815ef..9aa9c5a46 100644
--- a/src/curry/debounce.ts
+++ b/src/curry/debounce.ts
@@ -41,24 +41,20 @@ export function debounce<TArgs extends any[]>(
   func: (...args: TArgs) => any,
 ): DebounceFunction<TArgs> {
   let timer: unknown = undefined
-  let active = true
 
   const debounced: DebounceFunction<TArgs> = (...args: TArgs) => {
-    if (active) {
-      clearTimeout(timer)
-      timer = setTimeout(() => {
-        active && func(...args)
-        timer = undefined
-      }, delay)
-    } else {
+    clearTimeout(timer)
+    timer = setTimeout(() => {
       func(...args)
-    }
+      timer = undefined
+    }, delay)
   }
   debounced.isPending = () => {
     return timer !== undefined
   }
   debounced.cancel = () => {
-    active = false
+    clearTimeout(timer)
+    timer = undefined
   }
   debounced.flush = (...args: TArgs) => func(...args)
 
diff --git a/tests/curry/debounce.test.ts b/tests/curry/debounce.test.ts
index 1c0d2bd56..65c16994d 100644
--- a/tests/curry/debounce.test.ts
+++ b/tests/curry/debounce.test.ts
@@ -27,14 +27,23 @@ describe('debounce', () => {
     expect(mockFunc).toHaveBeenCalledTimes(1)
   })
 
-  test('does not debounce after cancel is called', () => {
-    runFunc3Times()
+  test('does not execute if cancel called before timeout', () => {
+    func()
+    expect(func.isPending()).toBe(true);
+    func.cancel()
+    expect(func.isPending()).toBe(false);
+    vi.advanceTimersByTime(delay + 10)
     expect(mockFunc).toHaveBeenCalledTimes(0)
+  })
+
+  test('continues to debounce after cancel is called', () => {
+    func()
     func.cancel()
-    runFunc3Times()
-    expect(mockFunc).toHaveBeenCalledTimes(3)
-    runFunc3Times()
-    expect(mockFunc).toHaveBeenCalledTimes(6)
+    vi.advanceTimersByTime(delay + 10)
+    expect(mockFunc).toHaveBeenCalledTimes(0)
+    func()
+    vi.advanceTimersByTime(delay + 10)
+    expect(mockFunc).toHaveBeenCalledTimes(1)
   })
 
   test('executes the function immediately when the flush method is called', () => {