I have a series of objects that have an attribute of data-b='[0-9]', and I'm using jQuery to determine what the last value in the list is, up to that point. Here's what I have:

<div data-b="0">
 <div></div>
</div>

<div data-b="1">
 <div></div>
</div>

<div data-b="2">
 <div></div>
</div>

<script>
var lB = $('div').last().data('b');
alert(lB);
</script>

Here's the craziness: as it's written above, I get an alert of "undefined". But if I take out the empty child <div></div>, it alerts with the number 2, as expected.

I also tried using $('div').last().attr('data-b');, but had the same result.

This Javascript (not jQuery) DID work. I haven't benchmarked it, though, and I think it will be about 1 million times slower than last():

var lB = 0;

for (var i=0; i < document.getElementsByTagName('div').length; i++) {
 var el = document.getElementsByTagName('div')[i];

 if (el.getAttribute('data-b'))
  lB = el.getAttribute('data-b');
}

alert(lB);

My third thought is to modify each <div data-b='[0-9]'></div> to include <script>lB++</script> after it. But that would require a manual modification to every page, so I'm thinking of that as a last resort.

Can you guys suggest a better way of getting this value?