title: Appinventor test empty string
body: <p>What is the best way to test if string is empty?</p>
  
  <p>I know it is possible to use if/else condition but is there possibility to use while loop?</p>
  
  <p>I used both variants but in my case (see on picture) the while loop do not work and still get the empty string error. And is there some more elegant way to evaluate more fields in one while loop?</p>
  
  <p><a href="https://i.stack.imgur.com/ecnCV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ecnCV.png" alt="Screenshot"></a></p>