feat(sfc): add defineEmits and deprecate defineEmit (#3725)

packages/runtime-core/__tests__/apiSetupHelpers.spec.ts

@@ -5,15 +5,15 @@ import {
   render,
   SetupContext
 } from '@vue/runtime-test'
-import { defineEmit, defineProps, useContext } from '../src/apiSetupHelpers'
+import { defineEmits, defineProps, useContext } from '../src/apiSetupHelpers'
 
 describe('SFC <script setup> helpers', () => {
   test('should warn runtime usage', () => {
     defineProps()
     expect(`defineProps() is a compiler-hint`).toHaveBeenWarned()
 
-    defineEmit()
-    expect(`defineEmit() is a compiler-hint`).toHaveBeenWarned()
+    defineEmits()
+    expect(`defineEmits() is a compiler-hint`).toHaveBeenWarned()
   })
 
   test('useContext (no args)', () => {

packages/runtime-core/src/apiSetupHelpers.ts

@@ -38,17 +38,17 @@ export function defineProps() {
   return null as any
 }
 
-export function defineEmit<
+export function defineEmits<
   TypeEmit = undefined,
   E extends EmitsOptions = EmitsOptions,
   EE extends string = string,
   InferredEmit = EmitFn<E>
 >(emitOptions?: E | EE[]): TypeEmit extends undefined ? InferredEmit : TypeEmit
 // implementation
-export function defineEmit() {
+export function defineEmits() {
   if (__DEV__) {
     warn(
-      `defineEmit() is a compiler-hint helper that is only usable inside ` +
+      `defineEmits() is a compiler-hint helper that is only usable inside ` +
         `<script setup> of a single file component. Its arguments should be ` +
         `compiled away and passing it at runtime has no effect.`
     )
@@ -56,6 +56,11 @@ export function defineEmit() {
   return null as any
 }
 
+/**
+ * @deprecated use `defineEmits` instead.
+ */
+export const defineEmit = defineEmits
+
 export function useContext(): SetupContext {
   const i = getCurrentInstance()!
   if (__DEV__ && !i) {

packages/runtime-core/src/index.ts

@@ -44,7 +44,12 @@ export { provide, inject } from './apiInject'
 export { nextTick } from './scheduler'
 export { defineComponent } from './apiDefineComponent'
 export { defineAsyncComponent } from './apiAsyncComponent'
-export { defineProps, defineEmit, useContext } from './apiSetupHelpers'
+export {
+  defineProps,
+  defineEmits,
+  defineEmit,
+  useContext
+} from './apiSetupHelpers'
 
 // Advanced API ----------------------------------------------------------------