Sample

From http://blog.stevensanderson.com/2010/07/05/introducing-knockout-a-ui-library-for-javascript/

<!doctype html>
<html lang=en>
  <head>
    <script type="text/javascript" src="jquery-1.4.2.min.js"></script>
    <script type="text/javascript" src="knockout-1.2.0.js"></script>
    <script type="text/javascript">
        jQuery(function() {
            var viewModel = {
                personName : ko.observable("Bert") // Initial state
            };
            ko.applyBindings(viewModel); // This makes Knockout get to work
        });
    </script>
    <title>introducing knockout.js</title>
    <meta charset=utf-8>
  </head>
  <body>
    Enter your name:
    <input id="source" data-bind="value: personName, valueUpdate: 'keyup'" />
    <div data-bind="visible: personName().length > 5">
      Wow, what a long name you have.
    </div>
  </body>
</html>