Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div id='a' ng-controller="MyCtrl">
    <div ng-class="['box', class, {true:'mini', false: 'large'}[!isMaximized]]">mini</div>
    <div ng-class="['box', class, class2, {true:'mini', false: 'large'}[isMaximized]]">large</div>
    <div ng-class="['box', class, class2, {undefined:'undef', null:'undef'}[isMinimized]]">undefined</div>
</div>

CSS

.mini{
  font-size: 1em;
  color:red;
}
.large{
   font-size:3em;
   color:blue;
}
.a.b{
    text-transform: uppercase;
}
.c.d{
    text-transform: lowercase;
}
.undef{
    color:orange;
}

JavaScript

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

function MyCtrl($scope) {
    $scope.isMaximized = false;
    $scope.class = 'a b';
    $scope.class2 = ['c', 'd'].join(' ');
    $scope.isMinimized = null;
}