fix(createEventHook): make createEventHook union type can be inferred…

… correctly

fix #3565

packages/shared/createEventHook/index.test.ts

@@ -93,6 +93,19 @@ describe('createEventHook', () => {
     expect(result).toEqual([2])
   })
 
+  it('should pass union type', () => {
+    let count = 0
+
+    const { on: onResult, trigger } = createEventHook<number | string>()
+
+    // union type should be inferred
+    onResult(value => count = 2)
+    trigger(1)
+    trigger(2)
+
+    expect(count).toBe(2)
+  })
+
   it('the same listener should fire only once', () => {
     const listener = vi.fn()
     const { on, trigger, off } = createEventHook<string>()

packages/shared/createEventHook/index.ts

@@ -5,8 +5,8 @@
 import { tryOnScopeDispose } from '../tryOnScopeDispose'
 
 type Callback<T> = T extends void ? () => void : (param: T) => void
-export type EventHookOn<T = any> = (fn: Callback<T>) => { off: () => void }
-export type EventHookOff<T = any> = (fn: Callback<T>) => void
+export type EventHookOn<T = any> = (fn: (param: T) => void) => { off: () => void }
+export type EventHookOff<T = any> = (fn: (param: T) => void) => void
 export type EventHookTrigger<T = any> = (param?: T) => Promise<unknown[]>
 
 export interface EventHook<T = any> {
@@ -21,13 +21,13 @@ export interface EventHook<T = any> {
  * @see https://vueuse.org/createEventHook
  */
 export function createEventHook<T = any>(): EventHook<T> {
-  const fns: Set<Callback<T>> = new Set()
+  const fns: Set<(param: T) => void> = new Set()
 
-  const off = (fn: Callback<T>) => {
+  const off = (fn: (param: T) => void) => {
     fns.delete(fn)
   }
 
-  const on = (fn: Callback<T>) => {
+  const on = (fn: (param: T) => void) => {
     fns.add(fn)
     const offFn = () => off(fn)