title: comma inside if statment in javascript
body: <p><br/>
  I've searched in SO but I didn't find something similar. Maybe I am using wrong search keys.<br/>
  I was editing a javascript library when I found this <code>if</code> statment</p>
  
  <pre><code>    var a = location.hash.replace(/^#/, "");
  
      if (container = $("#content"), a) {
         ..content
      } else {
          ...other code
      }
  </code></pre>
  
  <p>the first part <code>container = $("#content")</code> is assigning the value of  <code>$("#content")</code> to container but I don't understand why there is a comma inside the If. Is it like an <code>AND</code> operator?
  Something like  <code>if (container = $("#content") &amp;&amp; a)</code> ?
  What is it evaluating?</p>