fix(useAsyncState): improve types (#1119)

Co-authored-by: Anthony Fu <anthonyfu117@hotmail.com>

packages/core/useAsyncState/index.ts

@@ -1,16 +1,16 @@
 import { noop, promiseTimeout } from '@vueuse/shared'
-import type { Ref } from 'vue-demi'
+import type { Ref, ShallowRef } from 'vue-demi'
 import { ref, shallowRef } from 'vue-demi'
 
-export interface UseAsyncStateReturn<T> {
-  state: Ref<T>
+export interface UseAsyncStateReturn<Data, Shallow extends boolean> {
+  state: Shallow extends true ? ShallowRef<Data> : Ref<Data>
   isReady: Ref<boolean>
   isLoading: Ref<boolean>
   error: Ref<unknown>
-  execute: (delay?: number, ...args: any[]) => Promise<T>
+  execute: (delay?: number, ...args: any[]) => Promise<Data>
 }
 
-export interface AsyncStateOptions {
+export interface AsyncStateOptions<Shallow extends boolean> {
   /**
    * Delay for executing the promise. In milliseconds.
    *
@@ -49,7 +49,7 @@ export interface AsyncStateOptions {
    *
    * @default true
    */
-  shallow?: boolean
+  shallow?: Shallow
 }
 
 /**
@@ -61,20 +61,20 @@ export interface AsyncStateOptions {
  * @param initialState    The initial state, used until the first evaluation finishes
  * @param options
  */
-export function useAsyncState<T>(
-  promise: Promise<T> | ((...args: any[]) => Promise<T>),
-  initialState: T,
-  options: AsyncStateOptions = {},
-): UseAsyncStateReturn<T> {
+export function useAsyncState<Data, Shallow extends boolean = true>(
+  promise: Promise<Data> | ((...args: any[]) => Promise<Data>),
+  initialState: Data,
+  options?: AsyncStateOptions<Shallow>,
+): UseAsyncStateReturn<Data, Shallow> {
   const {
     immediate = true,
     delay = 0,
     onError = noop,
     resetOnExecute = true,
     shallow = true,
-  } = options
+  } = options ?? {}
 
-  const state = shallow ? shallowRef(initialState) : ref(initialState) as Ref<T>
+  const state = shallow ? shallowRef(initialState) : ref(initialState)
   const isReady = ref(false)
   const isLoading = ref(false)
   const error = ref<unknown | undefined>(undefined)
@@ -105,14 +105,14 @@ export function useAsyncState<T>(
     }
 
     isLoading.value = false
-    return state.value
+    return state.value as Data
   }
 
   if (immediate)
     execute(delay)
 
   return {
-    state,
+    state: state as Shallow extends true ? ShallowRef<Data> : Ref<Data>,
     isReady,
     isLoading,
     error,