title: Clipboard.js doesn't work with a tiny test
body: <p>I am faced with a little problem, I try to use clipboard.js, but it doesn't work even in my test. My html is as following, please tell me what I have done wrong.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
  &lt;head&gt;
    &lt;title&gt;test&lt;/title&gt;
    &lt;meta name="description" content="test" /&gt;
  
    &lt;meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no"&gt;
  
    &lt;meta name="viewport" content="width=device-width, initial-scale=1.0"&gt;
  
    &lt;script src="https://cdnjs.cloudflare.com/ajax/libs/clipboard.js/2.0.0/clipboard.min.js"&gt;&lt;/script&gt;
  &lt;/head&gt;
  
  &lt;body content="text/html"&gt;
  &lt;button class="btn" data-clipboard-demo="" data-clipboard-action="copy" data-clipboard-text="Just because you can doesn't mean you should â€” clipboard.js"&gt;Copy to clipboard&lt;/button&gt;
  &lt;/body&gt;
  &lt;/html&gt;</code></pre>
  </div>
  </div>
  </p>