Toggle CSS class Knockoutjs

From blog post example: http://stevemgentile.wordpress.com/2012/01/27/knockoutjs-toggling-css-class/

by Rene Rubio

HTML

<p>Click on a year:</p>
<ul data-bind="foreach: years">
    <li data-bind="text: $data, click: $parent.year, css:{selected_year: $parent.year() === $data}"></li>
</ul>
<hr/>
<div data-bind="text: year"/>

CSS

.selected_year{
    color: red;
}

JavaScript

function ViewModel(){
    var self = this;
    self.year = ko.observable("");
    self.years = ko.observableArray([]);
}

var vm = new ViewModel();
vm.years.push("1970");
vm.years.push("1980");

ko.applyBindings(vm);