title: merge two arrays with a separator, javascript
body: <p>I am trying to merge two arrays and have a separator included between all values (comma).  I tried this:</p>
  
  <pre><code>var aAndBWithCommasInBetween = a.concat(b);
  </code></pre>
  
  <p>But that leads to:</p>
  
  <pre><code>DealerOrigin
  </code></pre>
  
  <p>instead of:</p>
  
  <pre><code>Dealer, Origin
  </code></pre>
  
  <p>each a and b can have many values or none.</p>