title: How to get data attribute of option tag in JavaScript
body: <p>Want to get data attribute value from selected dropdown option.</p>
  
  <pre><code>&lt;select name="selection" id="mySelect"&gt;
      &lt;option value="21" data-rc="25" data-clnc="10"&gt;Treatment&lt;/option&gt;
  &lt;/select&gt;
  
  var rc = ? //value of data-rc
  var clnc = ? //value of data-clnc
  </code></pre>
  
  <p>No jQuery please only JavaScript :)</p>