Vuejs: You are mounting an instance with a template to `<body>`
<p>I got the following error:</p>

<p>vue.common.js?e881:987 </p>

<blockquote>
  <p>[Vue warn]: You are mounting an instance with a template to <code>&lt;body&gt;</code>. This will replace  entirely. You should probably use <code>replace: false</code> here.</p>
</blockquote>

<p>I'm using <code>vue-webpack</code> template and vue-router:</p>

<p>Here's my <code>main.js</code>:</p>

<pre><code>var Vue = require('vue');
var VueRouter = require('vue-router');

var App = require('./App');

Vue.use(VueRouter);

var router = new VueRouter();

router.map({
});

router.start(App, 'body');
</code></pre>

<p>So, where should I write the option <code>replace: false</code>?</p>

<p><code>App.vue</code>:</p>

<pre><code>&lt;template&gt;
    The site title is：{{html_title}}
    &lt;div&gt;
        &lt;input v-model="parentMsg"/&gt;
        &lt;br/&gt;

        &lt;p&gt;{{ parentMsg }}&lt;/p&gt;
    &lt;/div&gt;
&lt;/template&gt;

&lt;script&gt;
    export default {
        props: ['html_title'],
        components: {},
        data: function () {
            return {
                parentMsg: 'test'
            };
        }
    }
&lt;/script&gt;
</code></pre>