title: How to add or remove a className on event in ReactJS?
body: <p>I am quite new to React and I am struggling a little with converting my thinking from standard js.</p>
  
  <p>In my react component I have the following element:</p>
  
  <pre><code>&lt;div className='base-state' onClick={this.handleClick}&gt;click here&lt;/div&gt;
  </code></pre>
  
  <p>The behaviour I am looking for is to add an extra class on click.  My first idea was to try and add the class in the click handler function e.g.</p>
  
  <pre><code>handleClick : function(e) {
     &lt;add class "click-state" here&gt;
  }
  </code></pre>
  
  <p>I haven't been able to find any examples that do anything similar though, so I am fairly sure I am not thinking about this in the right way.</p>
  
  <p>Can anyone point me in the right direction?</p>