title: Regular expression - String cannot start, end with white-space and consist of few white-spaces in a row
body: <p>I am looking for  regular expression that allow strings that does not start and does not end with white-space and does not consist of few white-spaces in a row.</p>
  
  <p>Allow:</p>
  
  <pre><code>asd asd asd,
  asdasd,
  asd asd,
  </code></pre>
  
  <p>Disallow:</p>
  
  <pre><code>asd   asdasd,
   asdasd,
  asdasd  ,
  </code></pre>