消息订阅与发布(pubsub) 消息订阅与发布是一种组件间通信的方式，适用于任意组件间通信
使用步骤
1.安装 pubsub, npm i pubsub-js
2.引入: import pubsub from ‘pubsub-js’
3.接收数据: A组件想接收数据，则在A组件中订阅消息，订阅的回调留在A组件中
export default {
methods: {
demo(msgName, data) {...}
}
...
mounted() {
this.pid = pubsub.subscribe('xxx',this.demo)
}
}
4.提供数据: pubsub.publish(‘xxx’,data)
5.最好再 beforeDestroy 钩子中，使用 pubsub.unsubscribe(pid) 取消订阅
src/components/School.vue
<template>
<div class="school">
<h2>学校名称：{{name}}</h2>
<h2>学校地址：{{address}}</h2>
</div>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name: 'School',
data() {
return {
name:'尚硅谷',
address:'北京',
}
},
methods: {
demo(msgName, data) {
console.log('我是School组件，收到了数据：',msgName, data)
}
},
mounted() {
this.pubId = pubsub.subscribe('demo', this.demo) // 订阅消息
},
beforeDestroy() {
pubsub.unsubscribe(this.pubId) // 取消订阅
}
}
</script>
<style scoped>
.school{
background-color: skyblue;
padding: 5px;
}
</style>
2.src/components/Student.vue
<template>
<div class="student">
<h2>学生姓名：{{name}}</h2>
<h2>学生性别：{{sex}}</h2>
<button @click="sendStudentName">把学生名给School组件</button>
</div>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:'Student',
data() {
return {
name:'JOJO',
sex:'男',
}
},
methods: {
sendStudentName(){
pubsub.publish('demo', this.name) // 发布消息
}
}
}
</script>
<style scoped>
.student{
background-color: pink;
padding: 5px;
margin-top: 30px;
}
</style>
使用消息的订阅与发布优化 Todo-List
src/App.vue
<template>
<div id="root">
<div class="todo-container">
<div class="todo-wrap">
<MyHeader @addTodo="addTodo"/>
<MyList :todos="todos"/>
<MyFooter :todos="todos" @checkAllTodo="checkAllTodo" @clearAllTodo="clearAllTodo"/>
</div>
</div>
</div>
</template>
<script>
import pubsub from 'pubsub-js' // 习惯第三方库写上面
import MyHeader from './components/MyHeader.vue'
import MyList from './components/MyList.vue'
import MyFooter from './components/MyFooter.vue'
export default {
name:'App',
components: { MyHeader,MyList,MyFooter },
data() {
return {
todos:JSON.parse(localStorage.getItem('todos')) || []
}
},
methods:{
//添加一个todo
addTodo(todoObj){
this.todos.unshift(todoObj)
},
//勾选or取消勾选一个todo
checkTodo(_,id){
this.todos.forEach((todo)=>{
if(todo.id === id) todo.done = !todo.done
})
},
//删除一个todo
deleteTodo(id){
this.todos = this.todos.filter(todo => todo.id !== id)
},
//全选or取消勾选
checkAllTodo(done){
this.todos.forEach(todo => todo.done = done)
},
//删除已完成的todo
clearAllTodo(){
this.todos = this.todos.filter(todo => !todo.done)
}
},
watch:{
todos:{
deep:true,
handler(value){
localStorage.setItem('todos',JSON.stringify(value))
}
}
},
mounted(){
this.pubId = pubsub.subscribe('checkTodo',this.checkTodo) // 两种对比
this.$bus.$on('deleteTodo',this.deleteTodo)
},
beforeDestroy(){
pubsub.unsubscribe(this.pubId)
this.$bus.$off('deleteTodo')
}
}
</script>
<style>
body {
background: #fff;
}
.btn {
display: inline-block;
padding: 4px 12px;
margin-bottom: 0;
font-size: 14px;
line-height: 20px;
text-align: center;
vertical-align: middle;
cursor: pointer;
box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.2), 0 1px 2px rgba(0, 0, 0, 0.05);
border-radius: 4px;
}
.btn-danger {
color: #fff;
background-color: #da4f49;
border: 1px solid #bd362f;
}
.btn-danger:hover {
color: #fff;
background-color: #bd362f;
}
.btn:focus {
outline: none;
}
.todo-container {
width: 600px;
margin: 0 auto;
}
.todo-container .todo-wrap {
padding: 10px;
border: 1px solid #ddd;
border-radius: 5px;
}
</style>
src/components/myItem.vue
<template>
<li>
<label>
<input type="checkbox" :checked="todo.done" @click="handleCheck(todo.id)"/>
<span>{{todo.title}}</span>
</label>
<button class="btn btn-danger" @click="handleDelete(todo.id,todo.title)">删除</button>
</li>
</template>
<script>
import pubsub from 'pubsub-js'
export default {
name:'MyItem',
props:['todo'],
methods:{
handleCheck(id){
pubsub.publish('checkTodo',id)
},
handleDelete(id,title){
if(confirm("确定删除任务："+title+"吗？")){
this.$bus.$emit('deleteTodo',id)
}
}
}
}
</script>
<style scoped>
li {
list-style: none;
height: 36px;
line-height: 36px;
padding: 0 5px;
border-bottom: 1px solid #ddd;
}
li label {
float: left;
cursor: pointer;
}
li label li input {
vertical-align: middle;
margin-right: 6px;
position: relative;
top: -1px;
}
li button {
float: right;
display: none;
margin-top: 3px;
}
li:before {
content: initial;
}
li:last-child {
border-bottom: none;
}
li:hover {
background-color: #eee;
}
li:hover button{
display: block;
}
</style>