Knockoutjs.com - Hello World Example

http://knockoutjs.com/examples/helloWorld.html

HTML

<script src="http://knockoutjs.com/downloads/knockout-3.0.0.js"></script>
<link rel="stylesheet" href="//netdna.bootstrapcdn.com/bootstrap/3.0.2/css/bootstrap.min.css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.0.2/js/bootstrap.min.js"></script>
<div class="btn-group">
  <label class="btn btn-primary">
    <input type="radio" name="options" id="option1" value="1" data-bind="checked: optionsValue"> Option 1
  </label>
  <label class="btn btn-primary">
    <input type="radio" name="options" id="option2" value="2" data-bind="checked: optionsValue"> Option 2
  </label>
  <label class="btn btn-primary">
    <input type="radio" name="options" id="option3" value="3" data-bind="checked: optionsValue"> Option 3
  </label>
</div>
<br />
<span data-bind="text: optionsValue"></span>

JavaScript

var ViewModel = function() {
    this.optionsValue = ko.observable()
};
 
ko.applyBindings(new ViewModel());