title: Knockout validation with HTML5 attributes
body: <p>Can I just add HTML5 attributes to my element to wireup validation? </p>
  
  <p>If so it doesn't seem to be working for me. Do I need to do something extra?</p>
  
  <p><a href="http://jsfiddle.net/FcM2A/1/" rel="nofollow">http://jsfiddle.net/FcM2A/1/</a></p>
  
  <pre><code>vm required&lt;input data-bind="value: num1, valueUpdate: 'afterkeydown'"/&gt;&lt;br/&gt;
  HTML5 required&lt;input required="true" data-bind="value: num2, valueUpdate: 'afterkeydown'" /&gt;&lt;br/&gt;
  num1 isValid: &lt;span data-bind="text: num1.isValid()"&gt;&lt;/span&gt;&lt;br/&gt;
  num2 isValid: &lt;span data-bind="text: num2.isValid()"&gt;&lt;/span&gt;
  &lt;p data-bind="text:ko.toJSON($root)"&gt;&lt;/p&gt;
  
  ko.validation.init( {parseInputAttributes: true, writeInputAttributes: true} ); //enable HTML5 validation, write HTML5 validation attributes to the controls
  
  var viewModel = {
      num1: ko.observable("1").extend({ required: true }),
      num2: ko.observable("2")
  };
  ko.applyBindings(viewModel);
  </code></pre>