title: Add & Remove CSS classes with React
body: <p>I am new to React. I have a few buttons in a button group:</p>
  
  <pre><code>&lt;div className="btn-group"&gt;
      &lt;button className="btn btn-mini btn-default" onClick={() =&gt; this.changeDataType("type1")} &gt;Button1&lt;/button&gt;
      &lt;button className="btn btn-mini btn-default" onClick={() =&gt; this.changeDataType("type2")} &gt;Button2&lt;/button&gt;
      &lt;button className="btn btn-mini btn-default" onClick={() =&gt; this.changeDataType("type3")} &gt;Button3&lt;/button&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>Whenever the user clicks on one of the buttons, this button should become the active, selected one. I found out that I need to add the CSS class <code>active</code> to the corresponding button, but I am not sure how to implement this.</p>
  
  <p>I thought about this for a bit. I have a <code>changeDataType</code> function connected to my buttons, in which I do some other stuff. Would I then, in there, somehow manipulate the CSS?</p>
  
  <p>So I guess my questions are <em>first</em>, how to target the button I need to target, and <em>second</em>, how I could change that button's CSS with React.</p>