<!DOCTYPE html>
<html>
<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>$children</title>
    <style>
        template{
            display: none;
        }
    </style>
</head>
<body>
    <div id="app">
        <parent-component></parent-component>
    </div>
    <template id='parentComponent'>
        <!-- 组件最外层必须带一个标签 -->
        <div>
            <child