I have an unordered list like so:

```
<ul class="foo">
  <li id="asdf">
    <span class="indexnumber"></span>
    <span class="description">whatever</span>
  </li>

  <li id="asdfasdf">
    <span class="indexnumber"></span>
    <span class="description">whatever</span>
  </li>
</ul>

```

I want to display the index number of the list item in the indexnumber span (i.e., the first item will display 1, the second will display 2, and so on). My users will have the ability to sort the list items (using jquery ui sortable). I would like to be able to show my users a number in the list item that indicates where the list item is (and the value can change as the user re-orders the list).

How can I simply display the index position in the array using jquery? Alternately, is there an easy way to do this with the sortable events (i.e., once the list is sorted, increment or decrement the indexnumbers in all other list items as appropriate)?