title: how to add active class in ionic + angular?
body: <p>could you please tell me how to add active class in selected button .when use select any button from toolbar it become <strong>green</strong> and show data .Actually I have four button and four div contend .I need to show div contend when I select the button .In other words when I click <strong>"A button"</strong> it show "A contend ".When I click "B button " it show "b contend " now b button is active rest are inactive .can we do this angular .I tried to do using <strong>ng-if</strong> but succeed till now
  here is my code</p>
  
  <pre><code>&lt;html ng-app="ionicApp"&gt;
     &lt;head&gt;
        &lt;meta charset="utf-8"&gt;
        &lt;meta name="viewport" content="initial-scale=1, maximum-scale=1, user-scalable=no, width=device-width"&gt;
        &lt;title&gt;Tabs Example&lt;/title&gt;
        &lt;link href="//code.ionicframework.com/nightly/css/ionic.css" rel="stylesheet"&gt;
        &lt;script src="//code.ionicframework.com/nightly/js/ionic.bundle.js"&gt;&lt;/script&gt;
     &lt;/head&gt;
     &lt;body&gt;
     &lt;/body&gt;
     &lt;ion-view ng-controller="showhidecntr"&gt;
        &lt;ion-header-bar align-title="center" class="bar-balanced"&gt;
           &lt;div class="buttons"&gt;
              &lt;a class="button icon-left ion-chevron-left button-clear"&gt;Back&lt;/a&gt;
              &lt;!--i style="font-size:30px;" class='icon ion-chevron-left'&gt;&lt;/i--&gt;
           &lt;/div&gt;
           &lt;h1 class="title"&gt;Title&lt;/h1&gt;
        &lt;/ion-header-bar&gt;
        &lt;ion-content&gt;
           &lt;div class="button-bar"&gt;
              &lt;a class="button button-small"  ng-click="AbuttonClick"&gt;a &lt;/a&gt;
              &lt;a class="button button-small"  ng-click="BbuttonClick"&gt;b &lt;/a&gt;
              &lt;a class="button button-small"  ng-click="CbuttonClick"&gt;c&lt;/a&gt;
              &lt;a class="button button-small"  ng-click="DbuttonClick"&gt;d&lt;/a&gt;
           &lt;/div&gt;
           &lt;div class="a_content" ng-if='isShowAcontend'&gt;
              a contend
           &lt;/div&gt;
           &lt;div class="b_content" ng-if='isShowBcontend'&gt;
              b contend
           &lt;/div&gt;
           &lt;div class="c_content" ng-if='isShowCcontend'&gt;
              c contend
           &lt;/div&gt;
           &lt;div class="d_content" ng-if='isShowDcontend'&gt;
              d contend
           &lt;/div&gt;
        &lt;/ion-content&gt;
     &lt;/ion-view&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p><a href="http://codepen.io/anon/pen/JdErVM" rel="nofollow">http://codepen.io/anon/pen/JdErVM</a></p>