title: jQuery - delete last object by key
body: <p>Hi i have this object : </p>
  
  <pre><code>object {
   key1:[.....],
   key2:[....],
   key3:[.... ]
  }
  </code></pre>
  
  <p>how does i can delete the last object key (key3)?</p>
  
  <p>i would like to be free to delete last object key without knowing anything about that key.</p>