v - on

1. v-on绑定：on:click点击事件，再触发方法里面的add()或del()

2. 详情查看官方文档：https://cn.vuejs.org/v2/api/#v-on

 <!DOCTYPE html>
 <html lang="en">

 <head>
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <meta http-equiv="X-UA-Compatible" content="ie=edge">
     <title>Document</title>
     <!-- Step1.对于vue,可以用cdn -->
     <script src="https://cdn.bootcss.com/vue/2.5.17-beta.0/vue.min.js"></script>
     <style>
         #app div{
             padding: 2%;
             margin-bottom: 1%;
             border-bottom: 1px solid #ddd;
             background-color: blanchedalmond;
         }
     </style>
 </head>

 <body>

     <div id="app">
         <div>皮卡丘要嗑{{count}}瓶药</div>
         <button v-on:click="add">加</button>
         <button v-on:click="del">减</button>
     </div>

     <script type="text/javascript">
         var app = new Vue({
             el: '#app',
             // 初始化数据
             data: {
                 count: 1
             },
             // 方法.
             methods: {
                 add() {
                     this.count++;
                 },
                 del() {
                     this.count--;
                 }
             }
         })
     </script>
 </body>

 </html>