<body ng-app="myApp"> <input type="button" value="Add Class" ng-click="instance='newClass'" /> <input type="button" value="Remove Classs" ng-click="instance=''" /> <div class="defaultClass" ng-class="instance">Sample Text</div> </body>
var app = angular.module("myApp",[]);
div{ padding: 10px; color: #fff; }
.defaultClass{ background: #148fa1; }
.newClass { background: #2e7cb8; }