Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/1.2.0/angular.js"></script>
<script src="http://underscorejs.org/underscore.js"></script>
<div ng-app='myApp'>
<div ng-controller="Ctrl">
    <div ng-class="{'has-error' : popup, 'has-success':!popup}">
        <div id="patient" ng-class="{'popupOn' : popup, 'ng-valid':!popup}">test</div>
        <button ng-click="togglePopup()">toggleClass</button>
    </div>
</div>
</div>

CSS

.popupOn{
    background-color: #339933;
}
.has-error{
    border: 1px solid #ccc;
}

JavaScript

var myApp = angular.module('myApp',[]);
myApp.controller("Ctrl", function($scope){
    $scope.popup = false;
    $scope.togglePopup = function(){
        $scope.popup = !$scope.popup;
    }
});