title: dataset property doesn't work with objects?
body: <pre><code>el2.dataset.stuff = document.getElementById('el1');
  </code></pre>
  
  <p>doesn't seem to work.</p>
  
  <p>I need to be able to access the innerHTML property of el1, later.</p>
  
  <pre><code>el2.dataset.stuff = document.getElementById('el1').innerHTML;
  </code></pre>
  
  <p>works, but I don't like the idea of storing duplicate content in variables. If I have many elements, it would eat up a lot of memory.</p>
  
  <p>I guess because dataset requires strings? If that's true, how do I set reference to another elmement inside el2 ?</p>