title: ReactJS redirect
body: <p>I'm using <code>ReactJS</code> and <code>react-router</code> in my application. I need to do next thing: when user open the page - to check, if he logged in or no, and if yes, then to do redirect to <code>/auth</code> page. I'm doing next thing:</p>
  
  <pre><code>componentWillMount: function() {
      if (sessionStorage["auth"] == null) {
          this.transitionTo("/auth");
      }
  },
  </code></pre>
  
  <p>In browser url it really do redirect to <code>/auth</code>, render the <code>/auth</code> page and after override it with current component. So here the question: how to cancel rendering for the current component, or how to do redirect in other way? Thanks.</p>