title: Angular 2 call setInterval() undefined Services form Dependency injection
body: <p>I want to call a function every 10 minutes by using <em>setInterval()</em> and in this function I want to use a Service (called auth) that I get from the Dependency Injector of Angular 2, the problem is that the console tells me following: </p>
  
  <blockquote>
    <p>EXCEPTION: TypeError: this.auth is undefined</p>
  </blockquote>
  
  <pre><code>  constructor(private auth: AuthService){
      setInterval(function(){ this.auth.refreshToken(); }, 1000 * 60 * 10);
    }
  </code></pre>