title: How can I use setAttribute to set multiple classes on an element?
body: <p>How can I set an element to have multiple classes?</p>
  
  <p>Initial attempt: </p>
  
  <pre><code>element.setAttribute("class","class1","class2");
  element.className="class1 , class2";
  element.class="class1 , class2";
  </code></pre>