title: jQuery get ids of siblings
body: <p>I'm trying to get ids of siblings.</p>
  
  <pre><code>&lt;ul&gt;
      &lt;li id="a1"&gt;a1&lt;/li&gt;
      &lt;li id="a2"&gt;a2&lt;/li&gt;
      &lt;li id="a3"&gt;a3&lt;/li&gt;
      &lt;li id="a4"&gt;a4&lt;/li&gt;
  &lt;/ul&gt;
  </code></pre>
  
  <p>When I click on one of the li's, I want to select all sibling ids separated by comma.
  Ex. I click on #a2 and get #a1, #a3, #a4. Thanks.</p>