title: Regex to disallow more than 1 dash consecutively
body: <ol>
  <li>How can I disallow <code>--</code> (more than 1 consecutive -)? e.g. <code>ab--c</code></li>
  <li><code>-</code> at the back of words not allow, e.g. <code>abc-</code></li>
  <li><code>-</code> at start of words not allow, e.g. <code>-abc</code></li>
  </ol>
  
  <p><code>^[A-Za-z0-9-]+$</code> is what I have so far.</p>