title: Using attr binding in knockout with a boolean attribute 'autofocus'
body: <p>For some attributes, it is the presence of the attribute that has an effect - the value that is assigned to it is irrelevant. For example, the autofocus attribute can be set to 'false' or 'true, or 'banana' and the element is still gets automatically focused. IE, the following are all equivalent and cause the div to get focus :</p>
  
  <pre><code>&lt;div autofocus="false" contenteditable="true"&gt;&lt;/div&gt;
  &lt;div autofocus="true" contenteditable="true"&gt;&lt;/div&gt;
  &lt;div autofocus="banana" contenteditable="true"&gt;&lt;/div&gt;
  </code></pre>
  
  <p>Knockout has an 'attr' binding, but it seems to be only useful for <em>assigning</em> values <em>to</em> attributes, not for adding/removing attributes.</p>
  
  <p>Is there another way to do it in knockout, or am I forced to set it from javascript?</p>
  
  <p>NB Using chrome on ubuntu.</p>