Closest is not part of delegation. Closest is a way to traverse the
dom tree to find an elements parent that matches the selector used. I
think the reason this is helpful in event delegation is because some
browsers may not register the click if it occurs inside of a child
element of the li. For example, the source of the example
In document tree there are 2 list items, 1 of which has only a bold
element inside of it while the other has a text node and a bold node.
If you were using a browser which used event bubbling, I believe that
clicking inside of the bold element with a normal click event linked
directly to the li could actually interfere. Also, in the example
this was attached to the $(document) element not the ul element. This
could serve as another advantage. in your example above, there's only
1 ul that you are attaching to, but you may want to attach this to
several. $(document) would be a convenient way to do this.