Vue $mount实战之实现消息弹窗组件

之前的项目一直在使用Element-UI框架，element中的Notification、Message组件使用时不需要在html写标签，而是使用js调用。那时就很疑惑，为什么element ui使用this.$notify、this.$message就可以实现这样的功能？

1、实现消息弹窗组件的几个问题

• 如何在任何组件中使用this.$message就可以显示消息？
• 如何将消息的dom节点插入到body中？
• 同时出现多个消息弹窗时，消息弹窗的z-index如何控制？

2、效果预览

3、代码实现

PMessage.vue

@import "p-message.styl"

p-message.js

import Vue from 'vue';
import PMessage from './PMessage.vue';
import {popupManager} from "../../common/js/popup-manager";
let PMessageControl = Vue.extend(PMessage);
let count = 0;
// 存储message组件实例，如需有关闭所有message的功能就需要将每个message组件都存储起来
let instances = [];
const isVNode = function (node) {
 return node !== null && typeof node === 'object' && Object.prototype.hasOwnProperty.call(node, 'componentOptions');
};
const Message = function (options) {
 options = options || {};
 if(typeof options === 'string'){
 options = {
  message: options
 };
 }
 let id = 'message_' + ++count;
 let useronClose = options.onClose;
 // PMsesage.vue销毁时会调用传递进去的onClose，而onClose的处理就是将指定id的message组件从instances中移除
 options.onClose = function (){
 Message._close(id, userOnClose);
 };
 
 let instance = new PMessageControl({
 data: options
 });
 // 传递vNode
 if(isVNode(instance.message)){
 instance.$slots.default = [instance.message];
 instance.message = null;
 }
 instance.id = id;
 // 渲染元素，随后使用原生appendChild将dom插入到页面中
 instance.$mount();
 let $el = instance.$el;
 // message弹窗的z-index由popupManager来提供
 $el.style.zIndex = popupManager.getNextZIndex();
 document.body.appendChild($el);
 // 将message显示出来
 instance.show = true;
 console.log(instance)
 instances.push(instance);
 return instance;
};
// message简化操作
['success','error'].forEach(function (item) {
 Message[item] = options => {
 if(typeof options === 'string'){
  options = {
  message: options
  }
 }
 options.type = item;
 return Message(options);
 }
});

Message._close = function (id, userOnClose) {
 for(var i = 0, len = instances.length; i < len; i++){
 if(instances[i].id === id){
  if(typeof useronClose === 'function'){
  useronClose(instances[i]);
  }
  instances.splice(i, 1);
  break;
 }
 }
};
// 关闭所有message
Message.closeAll = function () {
 for(var i = instances.length - 1; i >= 0; i--){
 instances.close();
 }
};
export default Message;

popup-manager.js

let zIndex = 1000;
let hasZIndexInited = false;
const popupManager = {
 // 获取索引
 getNextZIndex(){
 if(!hasZIndexInited){
  hasZIndexInited = true;
  return zIndex;
 }
 return zIndex++;
 }
};
export {popupManager};
p-index.js
import pMessage from './p-message.js';
export default pMessage;
p-message.styl
.p-message{
 position: fixed;
 top: 20px;
 left: 50%;
 padding: 8px 15px;
 border-radius: 4px;
 background-color: #fff;
 color: #000;
 transform: translateX(-50%);
 transition: opacity .3s, transform .4s;
 &.message-fade-enter,
 &.message-fade-leave-to{
 opacity: 0;
 transform: translateX(-50%) translateY(-30px);
 }
 &.message-fade-enter-to,
 &.message-fade-leave{
 opacity: 1;
 transform: translateX(-50%) translateY(0);
 }
 &.error{
 color: #ff3737;
 }
 .p-message-icon{ 
 display: table-cell;
 vertical-align: middle;
 width: 64px;
 height: 45px;
 &.p-message-icon-success{
  background: url("../../assets/images/icons/message-icon/icon_success.png") no-repeat 0 0;
 }
 &.p-message-icon-error{
  background: url("../../assets/images/icons/message-icon/icon_error.png") no-repeat 0 0;
 }
 }
 .p-message-content{ 
 display: table-cell;
 vertical-align: middle;
 padding-left: 15px;
 }
}

main.js

// 引入pMessage组件
import pMessage from './components/p-message/p-index.js';
// 将pMessage绑定到Vue.prototype中。这样在组件中就可以通过this.$pMessage()的形式来使用了
Vue.prototype.$pMessage = pMessage;