support $on multi event (#4860)

Author: Kingwl

flow/component.js

@@ -41,7 +41,7 @@ declare interface Component {
   $set: (obj: Array<mixed> | Object, key: mixed, val: mixed) => void;
   $delete: (obj: Object, key: string) => void;
   $watch: (expOrFn: string | Function, cb: Function, options?: Object) => Function;
-  $on: (event: string, fn: Function) => Component;
+  $on: (event: string | Array<string>, fn: Function) => Component;
   $once: (event: string, fn: Function) => Component;
   $off: (event?: string, fn?: Function) => Component;
   $emit: (event: string, ...args: Array<mixed>) => Component;

src/core/instance/events.js

@@ -38,13 +38,19 @@ export function updateComponentListeners (
 
 export function eventsMixin (Vue: Class<Component>) {
   const hookRE = /^hook:/
-  Vue.prototype.$on = function (event: string, fn: Function): Component {
+  Vue.prototype.$on = function (event: string | Array<string>, fn: Function): Component {
     const vm: Component = this
-    ;(vm._events[event] || (vm._events[event] = [])).push(fn)
-    // optimize hook:event cost by using a boolean flag marked at registration
-    // instead of a hash lookup
-    if (hookRE.test(event)) {
-      vm._hasHookEvent = true
+    if (Array.isArray(event)) {
+      for (let i = 0, l = event.length; i < l; i++) {
+        this.$on(event[i], fn)
+      }
+    } else {
+      (vm._events[event] || (vm._events[event] = [])).push(fn)
+      // optimize hook:event cost by using a boolean flag marked at registration
+      // instead of a hash lookup
+      if (hookRE.test(event)) {
+        vm._hasHookEvent = true
+      }
     }
     return vm
   }

test/unit/features/instance/methods-events.spec.js

@@ -18,6 +18,19 @@ describe('Instance methods events', () => {
     expect(spy).toHaveBeenCalledWith(1, 2, 3, 4)
   })
 
+  it('$on multi event', () => {
+    vm.$on(['test1', 'test2'], function () {
+      expect(this).toBe(vm)
+      spy.apply(this, arguments)
+    })
+    vm.$emit('test1', 1, 2, 3, 4)
+    expect(spy.calls.count()).toBe(1)
+    expect(spy).toHaveBeenCalledWith(1, 2, 3, 4)
+    vm.$emit('test2', 5, 6, 7, 8)
+    expect(spy.calls.count()).toBe(2)
+    expect(spy).toHaveBeenCalledWith(5, 6, 7, 8)
+  })
+
   it('$once', () => {
     vm.$once('test', spy)
     vm.$emit('test', 1, 2, 3)

types/vue.d.ts

@@ -59,7 +59,7 @@ export declare class Vue {
     callback: WatchHandler<this, T>,
     options?: WatchOptions
   ): (() => void);
-  $on(event: string, callback: Function): this;
+  $on(event: string | string[], callback: Function): this;
   $once(event: string, callback: Function): this;
   $off(event?: string, callback?: Function): this;
   $emit(event: string, ...args: any[]): this;