title: Drag and Drop Divs and compare values
body: <p>I have four divs with custom Attributes like:</p>
  
  <pre><code>&lt;div marker="A"&gt;A1&lt;/div&gt;
  &lt;div marker="A"&gt;A2&lt;/div&gt;
  &lt;div marker="B"&gt;A3&lt;/div&gt;
  &lt;div marker="B"&gt;A4&lt;/div&gt;
  </code></pre>
  
  <p>Now I would like to use jquery to make each div drag- and drop-able.
  Now when a user drags e.g. div A1 on div A2 (vice-verca would alos be possible), it shall compare the marker attribute and if the marker happens to be the same, I want an alert to inform the user about this.</p>
  
  <p>How would I achieve that ? Can I use jquery-only or do I need a plugin for that ?</p>