title: Why is not isDevMode() working in my code at GCP
body: <p>I run this Angular app in Google cloud platform to test if the environment is <code>dev</code> or <code>prod</code>. I use the <code>isDevMode()</code> like this:</p>
  <pre><code>export class BookService {
  
    private BookItemsUrl: string;  // URL to web api
  
    constructor(private http: HttpClient) {
      // Return different backend path depending on runtime environment.
      if (isDevMode()) {
        // Localhost
        this.BookItemsUrl = 'api/BooksXml';
      } else {
        this.BookItemsUrl = 'https://my-back-bone.appspot.com/api/BooksXml';
      }
    }
  ..............
  </code></pre>
  <p>This works as expected on localhost, but not when deployed to GCP.
  I searched but can't see why this won't work.</p>
  <p>Any idea?</p>