title: Regex to match '-' delimited alphanumeric words
body: <p>I would like to test if user type only alphanumeric value or one "-".</p>
  
  <pre><code>hello-world                 -&gt; Match
  hello-first-world           -&gt; match
  this-is-my-super-world      -&gt; match
  hello--world                -&gt; NO MATCH
  hello-world-------this-is   -&gt; NO MATCH
  -hello-world                -&gt; NO MATCH (leading dash)
  hello-world-                -&gt; NO MATCH (trailing dash)
  </code></pre>
  
  <p>Here is what I have so far, but I dont know how to implement the "-" sign to test it if it is only once without repeating.</p>
  
  <pre><code>var regExp = /^[A-Za-z0-9-]+$/;
  </code></pre>