[英]Vue.js 3 Event Bus
How to create Event Bus in Vue 3?如何在 Vue 3 中创建事件总线?
In Vue 2, it was:在 Vue 2 中,它是:
export const bus = new Vue();
bus.$on(...)
bus.$emit(...)
In Vue 3, Vue
is not a constructor anymore, and Vue.createApp({});
在 Vue 3 中, Vue
不再是构造函数,而Vue.createApp({});
returns an object that has no $on
and $emit
methods.返回一个没有$on
和$emit
方法的 object。
As suggested in official docs you could use mitt library to dispatch events between components, let suppose that we have a sidebar and header
which contains a button that close/open the sidebar and we need that button to toggle some property inside the sidebar component:正如官方文档中所建议的,您可以使用mitt库在组件之间调度事件,假设我们有一个侧边栏和header
,其中包含一个关闭/打开侧边栏的按钮,我们需要该按钮来切换侧边栏组件内的某些属性:
in main.js import that library and create an instance of that emitter and define as a global property :在 main.js 中导入该库并创建该发射器的实例并定义为全局属性:
Installation:安装:
npm install --save mitt
Usage:用法:
import { createApp } from 'vue'
import App from './App.vue'
import mitt from 'mitt';
const emitter = mitt();
const app = createApp(App);
app.config.globalProperties.emitter = emitter;
app.mount('#app');
in header emit the toggle-sidebar
event with some payload:在 header 中发出带有一些有效负载的toggle-sidebar
事件:
<template>
<header>
<button @click="toggleSidebar"/>toggle</button>
</header>
</template>
<script >
export default {
data() {
return {
sidebarOpen: true
};
},
methods: {
toggleSidebar() {
this.sidebarOpen = !this.sidebarOpen;
this.emitter.emit("toggle-sidebar", this.sidebarOpen);
}
}
};
</script>
In sidebar receive the event with the payload:在侧边栏中接收带有有效负载的事件:
<template>
<aside class="sidebar" :class="{'sidebar--toggled': !isOpen}">
....
</aside>
</template>
<script>
export default {
name: "sidebar",
data() {
return {
isOpen: true
};
},
mounted() {
this.emitter.on("toggle-sidebar", isOpen => {
this.isOpen = isOpen;
});
}
};
</script>
For those using composition api they could use emitter
as follows:对于那些使用组合物 api 的人,他们可以使用emitter
,如下所示:
Create a file src/composables/useEmitter.js创建一个文件 src/composables/useEmitter.js
import { getCurrentInstance } from 'vue'
export default function useEmitter() {
const internalInstance = getCurrentInstance();
const emitter = internalInstance.appContext.config.globalProperties.emitter;
return emitter;
}
And from there on you can use useEmitter
just like you would with useRouter
:从那里你可以像使用useEmitter
一样使用useRouter
:
import useEmitter from '@/composables/useEmitter'
export default {
setup() {
const emitter = useEmitter()
...
}
...
}
Using the composition API使用组合API
You could also take benefit from the new composition API and define a composable event bus:您还可以从新组合 API 中受益并定义一个可组合的事件总线:
eventBus.js事件总线.js
import { ref } from "vue";
const bus = ref(new Map());
export default function useEventsBus(){
function emit(event, ...args) {
bus.value.set(event, args);
}
return {
emit,
bus
}
}
in component A do:在组件 A 中:
import useEventsBus from './eventBus';
...
//in script setup or inside the setup hook
const {emit}=useEventsBus()
...
emit('sidebarCollapsed',val)
in component B:在组件 B 中:
const { bus } = useEventsBus()
watch(()=>bus.value.get('sidebarCollapsed'), (val) => {
// destruct the parameters
const [sidebarCollapsedBus] = val ?? []
sidebarCollapsed.value = sidebarCollapsedBus
})
On version 3 of Vue.js, you can use either a third-party library, or use the functionality written in the publisher-subscriber(PubSub concept) programming pattern.在 Vue.js 的版本 3 上,您可以使用第三方库,或使用以发布者-订阅者(PubSub 概念)编程模式编写的功能。
event.js事件.js
//events - a super-basic Javascript (publish subscribe) pattern
class Event{
constructor(){
this.events = {};
}
on(eventName, fn) {
this.events[eventName] = this.events[eventName] || [];
this.events[eventName].push(fn);
}
off(eventName, fn) {
if (this.events[eventName]) {
for (var i = 0; i < this.events[eventName].length; i++) {
if (this.events[eventName][i] === fn) {
this.events[eventName].splice(i, 1);
break;
}
};
}
}
trigger(eventName, data) {
if (this.events[eventName]) {
this.events[eventName].forEach(function(fn) {
fn(data);
});
}
}
}
export default new Event();
index.js index.js
import Vue from 'vue';
import $bus from '.../event.js';
const app = Vue.createApp({})
app.config.globalProperties.$bus = $bus;
Content of EventBus class file: EventBus class 文件的内容:
class EventBusEvent extends Event {
public data: any
constructor({type, data} : {type: string, data: any}) {
super(type)
this.data = data
}
}
class EventBus extends EventTarget {
private static _instance: EventBus
public static getInstance() : EventBus {
if (!this._instance) this._instance = new EventBus()
return this._instance
}
public emit(type : string, data?: any) : void {
this.dispatchEvent(new EventBusEvent({type, data}))
}
}
export default EventBus.getInstance()
usage in project, emit event:在项目中使用,发出事件:
import EventBus from '...path to eventbus file with class'
//...bla bla bla... code...
EventBus.emit('event type', {..some data..}')
listen event:监听事件:
import EventBus from '...path to eventbus file with class'
//...bla bla bla... code...
EventBus.addEventListener('event type', (event) => { console.log(event.data) })
I've adapted another answer to have an equivalent interface to a Vue instance so that the utility works as a drop-in replacement that doesn't require changes in the consuming code.我已经调整了另一个答案,以具有与 Vue 实例等效的接口,以便该实用程序可以作为不需要更改使用代码的直接替代品。
This version also supports the $off
method with the first argument being an array of event names.此版本还支持$off
方法,第一个参数是事件名称数组。 It also avoids an issue in the $off
method were de-registering multiple event listeners would actually delete a wrong one due to iterating over the array in forwards direction while also deleting items from it.它还避免了$off
方法中的一个问题,即取消注册多个事件侦听器实际上会删除错误的事件侦听器,因为在向前方向上迭代数组同时还会从中删除项目。
event-bus.js
: event-bus.js
:
// @ts-check
/**
* Replacement for the Vue 2-based EventBus.
*
* @template EventName
*/
class Bus {
constructor() {
/**
* @type {Map<EventName, Array<{ callback: Function, once: boolean }>>}
*/
this.eventListeners = new Map()
}
/**
* @param {EventName} eventName
* @param {Function} callback
* @param {boolean} [once]
* @private
*/
registerEventListener(eventName, callback, once = false) {
if (!this.eventListeners.has(eventName)) {
this.eventListeners.set(eventName, [])
}
const eventListeners = this.eventListeners.get(eventName)
eventListeners.push({ callback, once })
}
/**
* See: https://v2.vuejs.org/v2/api/#vm-on
*
* @param {EventName} eventName
* @param {Function} callback
*/
$on(eventName, callback) {
this.registerEventListener(eventName, callback)
}
/**
* See: https://v2.vuejs.org/v2/api/#vm-once
*
* @param {EventName} eventName
* @param {Function} callback
*/
$once(eventName, callback) {
const once = true
this.registerEventListener(eventName, callback, once)
}
/**
* Removes all event listeners for the given event name or names.
*
* When provided with a callback function, removes only event listeners matching the provided function.
*
* See: https://v2.vuejs.org/v2/api/#vm-off
*
* @param {EventName | EventName[]} eventNameOrNames
* @param {Function} [callback]
*/
$off(eventNameOrNames, callback = undefined) {
const eventNames = Array.isArray(eventNameOrNames) ? eventNameOrNames : [eventNameOrNames]
for (const eventName of eventNames) {
const eventListeners = this.eventListeners.get(eventName)
if (eventListeners === undefined) {
continue
}
if (typeof callback === 'function') {
for (let i = eventListeners.length - 1; i >= 0; i--) {
if (eventListeners[i].callback === callback) {
eventListeners.splice(i, 1)
}
}
} else {
this.eventListeners.delete(eventName)
}
}
}
/**
* See: https://v2.vuejs.org/v2/api/#vm-emit
*
* @param {EventName} eventName
* @param {any} args
*/
$emit(eventName, ...args) {
if (!this.eventListeners.has(eventName)) {
return
}
const eventListeners = this.eventListeners.get(eventName)
const eventListenerIndexesToDelete = []
for (const [eventListenerIndex, eventListener] of eventListeners.entries()) {
eventListener.callback(...args)
if (eventListener.once) {
eventListenerIndexesToDelete.push(eventListenerIndex)
}
}
for (let i = eventListenerIndexesToDelete.length - 1; i >= 0; i--) {
eventListeners.splice(eventListenerIndexesToDelete[i], 1)
}
}
}
const EventBus = new Bus()
export default EventBus
old-event-bus.js
: old-event-bus.js
:
import Vue from 'vue'
const EventBus = new Vue()
export default EventBus
example.js
: example.js
:
// import EventBus from './old-event-bus.js'
import EventBus from './event-bus.js'
I just want to mention here that you can also use useEventBus defined by VueUse .在这里我只想提一下,你也可以使用VueUse定义的useEventBus 。
Here is one example for TypeScript so using an injection key.这是 TypeScript 的一个示例,因此使用注入密钥。
//myInjectionKey.ts
import type { EventBusKey } from '@vueuse/core'
export const myInjectionKey: EventBusKey<string> = Symbol('my-injection-key')
//emmitter
import { useEventBus } from '@vueuse/core'
import { mapInjectionKey } from "src/config/mapInjectionKey";
const bus = useEventBus(mapInjectionKey)
bus.emit("Hello")
//receiver
import { useEventBus } from '@vueuse/core'
import { mapInjectionKey } from "src/config/mapInjectionKey";
const bus = useEventBus(mapInjectionKey)
bus.on((e) => {
console.log(e) // "Hello"
})
With Vue composition and defineEmit you can even make it easier:使用 Vue 组合和defineEmit ,你甚至可以让它变得更简单:
<!-- Parent -->
<script setup>
import { defineEmit } from 'vue'
const emit = defineEmit(['selected'])
const onEmit = (data) => console.log(data)
</script>
<template>
<btnList
v-for="x in y"
:key="x"
:emit="emit"
@selected="onEmit"
/>
</template>
<!-- Children (BtnList.vue) -->
<script setup>
import { defineProps } from 'vue'
const props = defineProps({
emit: Function
})
</script>
<template>
<button v-for="x in 10" :key="x" @click="props.emit('selected', x)">Click {{ x }}</button>
</template>
I just showed it with one children, but you could pass though the emit function down to other children.我只是和一个孩子一起展示了它,但你可以将发射function 传递给其他孩子。
Using https://www.npmjs.com/package/vue-eventer means minimal code changes when migrating from Vue 2.x to Vue 3.0 (just initialization)...使用https://www.npmjs.com/package/vue-eventer意味着从 Vue 2.x 迁移到 Vue 3.0 时代码更改最少(仅初始化)...
// Vue 2.x
Vue.prototype.$eventBus = new Vue();
-> ->
// Vue 3.x
import VueEventer from 'vue-eventer';
YourVueApp.config.globalProperties.$eventBus = new VueEventer();
In a Vuejs project you can create a new file on the same root as App.vue and instanciate the Vue constructor.在 Vuejs 项目中,您可以在与 App.vue 相同的根目录中创建一个新文件并实例化 Vue 构造函数。
eventBus.js file eventBus.js 文件
import Vue from 'vue';
export default new Vue();
Then, you only have to import the event on every vue file you want to emit or receiving the event, like this:然后,您只需在要发出或接收事件的每个 vue 文件上导入事件,如下所示:
import EventBus from "../eventBus.js";
To just emit and receive the event use the $emit/$on mark要发出和接收事件,请使用 $emit/$on 标记
EventBus.$emit("evMsg", someData);
EventBus.$on("evMsg", (someData) => {});
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