Knockoutjs.com - Hello World Example

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

HTML

<script src="http://knockoutjs.com/downloads/knockout-3.2.0.js"></script>
<div class="form-group">
    <label for="price">Price:</label><i class="required"></i>
    <input id="price" type="text" class="form-control" data-bind="value: productPrice" />
</div>

JavaScript

// Here's my data model
var ViewModel = function() {
    this.productPrice = ko.observable(null);    
};
 
ko.applyBindings(new ViewModel()); // This makes Knockout get to work