title: Dart null / false / empty checking: How to write this shorter?
body: <p>This is my code for true on everything but empty string, null and false:</p>
  
  <pre><code>if (routeinfo["no_route"] == "" || routeinfo["no_route"] == null || routeinfo["no_route"] == false) {
      // do sth ...
  }
  </code></pre>
  
  <p>This is my code for true on everything but empty string, null, false or zero:</p>
  
  <pre><code>if (routeinfo["no_route"] == "" || routeinfo["no_route"] == null || routeinfo["no_route"] == false || routeinfo["no_route"] == 0) {
      // do sth...
  }
  </code></pre>
  
  <p>How can I write this shorter in Dart? Or is it not possible?</p>