How to add and remove class with AngularJS?

Question

I have a few buttons that work like switchers. If you click one it becomes active and "shuts down" other buttons. I did this using jQuery but would like to use AngularJS. Here is my code:

HTML

<div class="button-bar">
    <a class="button button-energized" id="weak">weak</a>
    <a class="button button-energized" id="normal">normal</a>
    <a class="button button-energized" id="strong">strong</a>
</div>

JavaScript

    .controller('AppCtrl', function($scope, $stateParams) {

        $('#weak').click(function() {
            $('#weak').addClass('active');
            $('#normal').removeClass('active');
            $('#strong').removeClass('active');
        });

        $('#normal').click(function() {
            $('#normal').addClass('active');
            $('#weak').removeClass('active');
            $('#strong').removeClass('active');
        });

        $('#strong').click(function() {
            $('#strong').addClass('active');
            $('#normal').removeClass('active');
            $('#weak').removeClass('active');
        });

   });

Answer 1

You could have ng-click that can toggle selected flag, that could be use with ng-class to bind / unbind class.

Markup

<div class="button-bar">
    <a class="button button-energized" id="weak" 
       ng-class="{active: $parent.selected=='weak'}" ng-click="$parent.selected='weak'">
      weak
    </a>
    <a class="button button-energized" id="normal" 
       ng-class="{active: selected=='normal'}" ng-click="selected='normal'">
        normal
    </a>
    <a class="button button-energized" id="strong" 
       ng-class="{active: selected=='strong'}" ng-click="selected='strong'">
        strong
    </a>
</div>

Working Fiddle

Better way

You could easily do this by using ng-repeat which will reduce your line of code.

Markup

$scope.strengths = ["weak","normal","strong"];

Code

<div class="button-bar">
    <a class="button button-energized" id="{{strength}}" 
       ng-class="{active: $parent.selected == strength}" 
       ng-click="$parent.selected=strength"
       ng-repeat="strength in strengths">
      {{strength}}
    </a>
</div>