vueuse
diff --git a/‎packages/shared/createEventHook/index.test.ts
Lines changed: 13 additions & 0 deletions b/‎packages/shared/createEventHook/index.test.ts
Lines changed: 13 additions & 0 deletions
diff --git a/‎packages/shared/createEventHook/index.ts
Lines changed: 11 additions & 1 deletion b/‎packages/shared/createEventHook/index.ts
Lines changed: 11 additions & 1 deletion
diff --git a/‎packages/shared/utils/types.ts
Lines changed: 7 additions & 0 deletions b/‎packages/shared/utils/types.ts
Lines changed: 7 additions & 0 deletions
@@ -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>()
 
@@ -2,9 +2,19 @@
  * The source code for this function was inspired by vue-apollo's `useEventHook` util
  * https://github.com/vuejs/vue-apollo/blob/v4/packages/vue-apollo-composable/src/util/useEventHook.ts
  */
+import type { IsAny } from '../utils/types'
 import { tryOnScopeDispose } from '../tryOnScopeDispose'
 
-type Callback<T> = T extends void ? () => void : (param: T) => void
+// any extends void = true
+// so we need to check if T is any first
+type Callback<T> = IsAny<T> extends true
+  ? (param: any) => void
+  : (
+      [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 EventHookTrigger<T = any> = (param?: T) => Promise<unknown[]>
 
@@ -148,3 +148,10 @@ export type MapOldSources<T, Immediate> = {
 }
 
 export type Mutable<T> = { -readonly [P in keyof T]: T[P] }
+
+// https://stackoverflow.com/questions/55541275/typescript-check-for-the-any-type
+export type IfAny<T, Y, N> = 0 extends (1 & T) ? Y : N
+/**
+ * will return `true` if `T` is `any`, or `false` otherwise
+ */
+export type IsAny<T> = IfAny<T, true, false>