ng-class

ng-class.html

<section>
    <p>
        <p>
            <span ng-class="{'label-success':focus}" class="label label-default">Focus!</span>
            <span ng-class="{'label-warning':!focus}" class="label label-default">Blur!</span>
        </p>
        <input ng-model="title" class="form-control" ng-focus="focus=true" ng-blur="focus=false" placeholder="Enter a title for your book"/>
        <div class="panel">
            <p> <h1> [[ focus ]]</h1> The title of your book is [[ title.length ? title : "No Name" ]] </p>
        </div>
    </p>
</section>