<template>
 <transition name="fade" @after-enter="handleAfterEnter">
  <div class="notification" :style="style" v-show="visible">
   <span class="notification__content">
    {{content}}
   </span>
   <span class="notification__btn" @click="handleClose">{{btn}}</span>
  </div>
 </transition>
</template>
<script>
export default {
 name: 'Notification',
 props: {
  content: {
   type: String,
   required: true
  },
  btn: {
   type: String,
   default: '关闭'
  }
 }
}
</script>
<style lang="less" scoped>
.fade-enter-active, .fade-leave-active{
 transition: opacity 1s;
}
.fade-enter, .fade-leave-to{
 opacity: 0;
}
.notification{
 display: flex;
 background-color: #303030;
 color: rgba(255, 255, 255, 1);
 align-items: center;
 padding: 20px;
 position: fixed;
 min-width: 280px;
 box-shadow: 0 3px 5px -1px rgba(0, 0, 0, 0.2), 0px 6px 10px 0px rgba(0, 0, 0, 0.3);
 flex-wrap: wrap;
 transition: all 0.3s;
 &__content{
  padding: 0;
 }
 &__btn{
  color: #ff4081;
  padding-left: 24px;
  margin-left: auto;
  cursor: pointer;
 }
}
</style>

import Vue from 'vue'
import Notification from './notification'

const NotificationConstructor = Vue.extend(Notification)

const instances = []
let seed = 1
const removeInstance = (instance) => {
 if (!instance) return
 const len = instances.length
 const index = instances.findIndex(ins => instance.id === ins.id)

 instances.splice(index, 1)

 if (len <= 1) return
 const removeHeight = instance.height
 for (let i = index; i < len - 1; i++) {
  instances[i].verticalOffset = parseInt(instances[i].verticalOffset) - removeHeight - 16
 }
}
const notify = (options = {}) => {
 if (Vue.prototype.$isServer) return
 // 获取vue实例
 let instance = new NotificationConstructor({
  propsData: options,
  data() {
   return {
    verticalOffset: 0,
    timer: null,
    visible: false,
    height: 0
   }
  },
  computed: {
   style() {
    return {
     position: 'fixed',
     right: '20px',
     bottom: `${this.verticalOffset}px`
    }
   }
  },
  mounted() {
   this.createTimer()
   this.$el.addEventListener('mouseenter', () => {
    if (this.timer) {
     this.clearTimer(this.timer)
    }
   })
   this.$el.addEventListener('mouseleave', () => {
    if (this.timer) {
     this.clearTimer(this.timer)
    }
    this.createTimer()
   })
  },
  updated() {
   this.height = this.$el.offsetHeight
  },
  beforeDestroy() {
   this.clearTimer()
  },
  methods: {
   createTimer() {
    this.timer = setTimeout(() => {
     this.visible = false
     document.body.removeChild(this.$el)
     removeInstance(this)
     this.$destroy()
    }, options.timeout || 3000)
   },
   clearTimer() {
    if (this.timer) {
     clearTimeout(this.timer)
    }
   },
   handleClose() {
    this.visible = false
    document.body.removeChild(this.$el)
    removeInstance(this)
    this.$destroy(true)
   },
   handleAfterEnter() {
    // eslint-disable-next-line no-debugger
    this.height = this.$el.offsetHeight
   }
  }
 })

 const id = `notification_${seed++}`
 instance.id = id
 // 生成vue中的$el
 instance = instance.$mount()
 // 将$el中的内容插入dom节点中去
 document.body.appendChild(instance.$el)
 instance.visible = true

 // eslint-disable-next-line no-unused-vars
 let verticalOffset = 0

 instances.forEach(item => {
  verticalOffset += item.$el.offsetHeight + 16
 })

 verticalOffset += 16
 instance.verticalOffset = verticalOffset

 instances.push(instance)

 return instance
}

export default notify

import Notification from './notification'
import notify from './notify'

export default (Vue) => {
 Vue.component(Notification.name, Notification)
 Vue.prototype.$notify = notify
}

import Notification from './components/notification'
Vue.use(Notification)

this.$notify({
 content: 'Hello'
})