title: What does export * (asterisk) mean in Angular/Typescript
body: <p>I was going through a <a href="https://stackblitz.com/edit/angular-6-communicating-between-components?file=app%2F_services%2Findex.ts" rel="nofollow noreferrer">component communication example</a> in Angular then I saw this:</p>
  
  <pre><code>export * from './message.service';
  </code></pre>
  
  <p>What is the role of this export action and why is it done in another file that is not message.service? (Yet in the message.service.ts there is an export function which exports the service class)</p>
  
  <pre><code>export class MessageService {...
  </code></pre>