feat(useArrayFindIndex): new function (#1973)

packages/shared/index.ts

@@ -34,6 +34,7 @@ export * from './until'
 export * from './useArrayEvery'
 export * from './useArrayFilter'
 export * from './useArrayFind'
+export * from './useArrayFindIndex'
 export * from './useArrayJoin'
 export * from './useArrayMap'
 export * from './useArrayReduce'

packages/shared/useArrayFindIndex/index.md

@@ -0,0 +1,36 @@
+---
+category: Array
+---
+
+# useArrayFindIndex
+
+Reactive `Array.findIndex`
+
+## Usage
+
+### Use with array of multiple refs
+
+```js
+import { useArrayFindIndex } from '@vueuse/core'
+const item1 = ref(0)
+const item2 = ref(2)
+const item3 = ref(4)
+const item4 = ref(6)
+const item5 = ref(8)
+const list = [item1, item2, item3, item4, item5]
+const result = useArrayFindIndex(list, i => i % 2 === 0)
+// result.value: 0
+item1.value = 1
+// result.value: 1
+```
+
+### Use with reactive array
+
+```js
+import { useArrayFindIndex } from '@vueuse/core'
+const list = ref([0, 2, 4, 6, 8])
+const result = useArrayFindIndex(list, i => i % 2 === 0)
+// result.value: 0
+list.value.unshift(-1)
+// result.value: 1
+```

packages/shared/useArrayFindIndex/index.test.ts

@@ -0,0 +1,37 @@
+import { ref } from 'vue-demi'
+import { useArrayFindIndex } from '.'
+
+describe('useArrayFindIndex', () => {
+  it('should be defined', () => {
+    expect(useArrayFindIndex).toBeDefined()
+  })
+
+  it('should work with array of refs', () => {
+    const item1 = ref(0)
+    const item2 = ref(2)
+    const item3 = ref(4)
+    const item4 = ref(6)
+    const item5 = ref(8)
+    const list = [item1, item2, item3, item4, item5]
+    const result = useArrayFindIndex(list, i => i % 2 === 0)
+    expect(result.value).toBe(0)
+    item1.value = 1
+    expect(result.value).toBe(1)
+    item2.value = 3
+    expect(result.value).toBe(2)
+    item3.value = 5
+    expect(result.value).toBe(3)
+    item4.value = 7
+    expect(result.value).toBe(4)
+    item5.value = 9
+    expect(result.value).toBe(-1)
+  })
+
+  it('should work with reactive array', () => {
+    const list = ref([0, 2, 4, 6, 8])
+    const result = useArrayFindIndex(list, i => i % 2 === 0)
+    expect(result.value).toBe(0)
+    list.value.unshift(-1)
+    expect(result.value).toBe(1)
+  })
+})

packages/shared/useArrayFindIndex/index.ts

@@ -0,0 +1,11 @@
+import type { MaybeComputedRef } from '@vueuse/shared'
+import { resolveUnref } from '@vueuse/shared'
+import type { ComputedRef } from 'vue-demi'
+import { computed } from 'vue-demi'
+
+export function useArrayFindIndex<T>(
+  list: MaybeComputedRef<MaybeComputedRef<T>[]>,
+  fn: (element: T, index: number, array: MaybeComputedRef<T>[]) => unknown,
+): ComputedRef<number> {
+  return computed(() => resolveUnref(list).findIndex((element, index, array) => fn(resolveUnref(element), index, array)))
+}

packages/shared/useArrayJoin/index.md

@@ -1,5 +1,5 @@
 ---
-category: Utilities
+category: Array
 ---
 
 # useArrayJoin