From bfb045f1007b922d637d4ec8211bfc57557e2443 Mon Sep 17 00:00:00 2001
From: Young Liang <younggglcy@gmail.com>
Date: Mon, 5 Sep 2022 18:05:01 +0800
Subject: [PATCH 1/2] fix(useArrayMap): allow return type matches the mapper
 function

fix [#2159](https://github.com/vueuse/vueuse/issues/2159)
---
 packages/shared/useArrayMap/index.test.ts | 12 ++++++++++++
 packages/shared/useArrayMap/index.ts      |  6 +++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/packages/shared/useArrayMap/index.test.ts b/packages/shared/useArrayMap/index.test.ts
index 1e10eca3111..d724e464e06 100644
--- a/packages/shared/useArrayMap/index.test.ts
+++ b/packages/shared/useArrayMap/index.test.ts
@@ -26,4 +26,16 @@ describe('useArrayMap', () => {
     list.value.pop()
     expect(result.value).toStrictEqual([0, 2, 4, 6])
   })
+
+  it('should match the return type of mapper function', () => {
+    const list = ref([0, 1, 2, 3])
+    const result1 = useArrayMap(list, i => i.toString())
+    result1.value.forEach(i => expect(i).toBeTypeOf('string'))
+
+    const result2 = useArrayMap(list, i => ({ value: i }))
+    result2.value.forEach((item, idx) => {
+      expect(item).toBeTypeOf('object')
+      expect(item).toHaveProperty('value', idx)
+    })
+  })
 })
diff --git a/packages/shared/useArrayMap/index.ts b/packages/shared/useArrayMap/index.ts
index 33d1a04fff2..7bdca057cc0 100644
--- a/packages/shared/useArrayMap/index.ts
+++ b/packages/shared/useArrayMap/index.ts
@@ -12,9 +12,9 @@ import { resolveUnref } from '../resolveUnref'
  *
  * @returns {Array} a new array with each element being the result of the callback function.
  */
-export function useArrayMap<T>(
+export function useArrayMap<T, U>(
   list: MaybeComputedRef<MaybeComputedRef<T>[]>,
-  fn: (element: T, index: number, array: T[]) => T,
-): ComputedRef<T[]> {
+  fn: (element: T, index: number, array: T[]) => U,
+): ComputedRef<U[]> {
   return computed(() => resolveUnref(list).map(i => resolveUnref(i)).map(fn))
 }

From ad532cf33ddf218b86c17ff75d4e1a5eb12e61e5 Mon Sep 17 00:00:00 2001
From: Young Liang <younggglcy@gmail.com>
Date: Mon, 5 Sep 2022 19:08:04 +0800
Subject: [PATCH 2/2] type(useArrayMap): set default value `T` to generics `U`

---
 packages/shared/useArrayMap/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/shared/useArrayMap/index.ts b/packages/shared/useArrayMap/index.ts
index 7bdca057cc0..85df85d3b42 100644
--- a/packages/shared/useArrayMap/index.ts
+++ b/packages/shared/useArrayMap/index.ts
@@ -12,7 +12,7 @@ import { resolveUnref } from '../resolveUnref'
  *
  * @returns {Array} a new array with each element being the result of the callback function.
  */
-export function useArrayMap<T, U>(
+export function useArrayMap<T, U = T>(
   list: MaybeComputedRef<MaybeComputedRef<T>[]>,
   fn: (element: T, index: number, array: T[]) => U,
 ): ComputedRef<U[]> {