VueJS does not bind inside iframe
<p>I have a VueJs code that used to work fine until I decided to put it into an iframe, then it is no longer binding data.</p>

<p>this is my code:</p>

<p><strong>HTML (GLOBAL)</strong></p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;title&lt;/title&gt;
  &lt;/head&gt;
  &lt;body&gt;
    &lt;div class="appbar"&gt;
      &lt;iframe src="/auth"&gt;&lt;/iframe&gt;
    &lt;/div&gt;
  &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p><strong>IFRAME CONTENT</strong></p>

<pre><code>&lt;!DOCTYPE html&gt;
&lt;html&gt;
  &lt;head&gt;
    &lt;script src="bower/vue/dist/vue.min.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  &lt;body id="auth"&gt;
    &lt;div&gt;{{foo}}&lt;/div&gt;
    &lt;script src="js/auth.js"&gt;&lt;/script&gt;
  &lt;/body&gt;
&lt;/html&gt;
</code></pre>

<p><strong>JAVASCRIPT</strong></p>

<pre><code>var auth = new Vue({
    el: '#auth',
    data: {
        foo: "I'm a text but don't appear"
    }
})
</code></pre>

<p>And this what I get:</p>

<p><a href="https://i.stack.imgur.com/LbSJn.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LbSJn.png" alt="enter image description here"></a></p>

<p>And the javascript seems to be working fine, when I tap in console <code>auth.foo</code> I get the right value:</p>

<p><a href="https://i.stack.imgur.com/ToIGp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ToIGp.png" alt="enter image description here"></a></p>