title: RegExp for allowing whitespaces but containing text
body: <p>I know the title might not be the most clearest of all, but i'm looking for a regexp that allows whitespaces (enter and space) but also checks if there is text available.</p>
  
  <p>For example what should and shouldn't be allowed:</p>
  
  <p>What should be allowed:</p>
  
  <pre><code>" text "
  </code></pre>
  
  <p>(this also goes for when using enters)</p>
  
  <p>What should not be allowed:</p>
  
  <pre><code>" " (or any number of whitespaces only)
  </code></pre>
  
  <p>Does anyone have any idea?</p>