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fix(types): enable proper type narrowing for defineEmits (#13935) #14150

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fix(types): enable proper type narrowing for defineEmits (#13935) #14150

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ebc4f0f
fix(types): enable proper type narrowing for defineEmits (#13935)
tuzixiangs Nov 30, 2025
ba68414
test: move issue 13935 test to setupHelpers.test-d.ts
tuzixiangs Dec 1, 2025
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19 changes: 19 additions & 0 deletions packages-private/dts-test/setupHelpers.test-d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -632,3 +632,22 @@ describe('defineOptions', () => {
expose: ['expose'],
})
})

describe('defineEmits w/ type declaration (Issue #13935)', () => {
const emit = defineEmits<{
open: [payload: number]
close: [payload: string]
}>()

// Correct usages
emit('open', 123)
emit('close', 'abc')

// Incorrect usages (should fail type check)
// @ts-expect-error
emit('open', 'string')
// @ts-expect-error
emit('close', 123)
// @ts-expect-error
emit('unknown', 123)
})
12 changes: 4 additions & 8 deletions packages/runtime-core/src/apiSetupHelpers.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,6 @@ import {
type IfAny,
type LooseRequired,
type Prettify,
type UnionToIntersection,
extend,
isArray,
isFunction,
Expand Down Expand Up @@ -151,13 +150,10 @@ export function defineEmits() {

export type ComponentTypeEmits = ((...args: any[]) => any) | Record<string, any>

type RecordToUnion<T extends Record<string, any>> = T[keyof T]

type ShortEmits<T extends Record<string, any>> = UnionToIntersection<
RecordToUnion<{
[K in keyof T]: (evt: K, ...args: T[K]) => void
}>
>
type ShortEmits<T extends Record<string, any>> = <K extends keyof T>(
evt: K,
...args: T[K]
) => void

/**
* Vue `<script setup>` compiler macro for declaring a component's exposed
Expand Down