Sorting Unordered Lists inside a Div using Javascript?

I'm very new to javascript. I'm trying to write a simple script to order alphabetically on load a series of UL's. Not the LI's inside of the UL's, but the UL's themselves.

Here is what the HTML looks like:

<div class="FindByCategory">

<ul>

<li>This is the first list item in the first unordered list</li>

<li>This is the second list item in the first unordered list</li>

</ul>

<ul>

<li>This is the first list item in the second unordered list</li>

<li>This is the second list item in the second unordered list</li>

</ul>

</div>

This is what I have so far:

<script>

function sortUnorderedList (div.FindByCategory, sortDescending) {

if(typeof div.FindByCategory == "string")

div = document.getElementById(div.FindByCategory);

var uls = ul.getElementsByTagName("UL");

var vals = [];

for(var i = 0, l = uls.length; i < l; i++)

vals.push(uls[i].innerHTML);

vals.sort();

for(var i = 0, l = uls.length; i < l; i++)

uls[i].innerHTML = vals[i];

}

</script>