Angular:

http://angularjs.org/

by mrajcok

HTML

<div ng-controller="MyCtrl">
    <div sibs>One</div>
    <div sibs>Two</div>
    <div sibs>Three</div>
</div>

CSS

.clicked { color: red; }

JavaScript

var app = angular.module('myApp',[]);

app.directive('sibs', function() {
    return {
        link: function(scope, element, attrs) {
            element.bind('click', function() {
                element.parent().children().removeClass('clicked');
                element.addClass('clicked');
            })
        },
    }
});

function MyCtrl($scope) {
}