title: Prevent knockout validation from evaluating on initial load
body: <p>I have a simple view-model with a few required attributes... I want each input to highlight red if the corresponding property is not valid, but I don't want this highlighting to display when the page is initially loaded... only when a value changes or when the user tries to save / continue...</p>
  
  <p>Right now it's validating the view-model on initial load because I'm specifying data-bind="css: { error: name.isValid() == false }", but I don't know of any other way to get this to work dynamically (similar to how jQuery unobtrusive validation works)...</p>
  
  <pre><code>var foo = { name: ko.observable().extend({required: true}) };
  
  &lt;div data-bind="css: { error: !name.isValid() }"&gt;
      &lt;input type="text" data-bind="value: name" /&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Any ideas on how to make this work would be appreciated... Thanks!</p>