title: Fancybox 3 - Add buttons to custom HTML popup
body: <p>I'm using fancybox 3, something like this</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
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  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;a href="#popup" data-fancybox="popup" data-buttons="['slideShow','fullScreen','thumbs','share']"&gt;Click me!&lt;/a&gt;
  
  &lt;div id="popup"&gt;MY POPUP with custom HTML&lt;/div&gt;</code></pre>
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  </div>
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  <p>However, no buttons get added, and I get a jQuery error "Cannot use 'in' operator to search for 'length' in ['slideShow','fullScreen','thumbs','share']". I've tried passing an object of options through data-options, but that did not work well. What is the correct syntax for what I am trying to do? I want to add some of the standard buttons, like the thumbnails preview, share button (if that's possible with custom HTML), etc</p>