Question

I have been banging my head on this one for too long.

I have a basic table (all the TR’s except the ones that include th’s are classes with classme)

<table>
<tr class="classme"><td>1</td></tr>
<tr class="classme"><td>1a</td></tr>
<tr class="classme"><td>2</td></tr>
<tr class="classme"><td>2a</td></tr>
<tr><th>skip me</th></tr>
<tr class="classme"><td>3</td></tr>
<tr class="classme"><td>3a</td></tr>
<tr ...><td>4</td></tr>
<tr ...><td>4a</td></tr>
<tr ...><td>5</td></tr>
<tr><td>5a</td></tr>
<tr><td>8</td></tr>
<tr><td>8a</td></tr>
<tr><td>9</td></tr>
<tr><td>9a</td></tr>
<tr><td>10</td></tr>
<tr><td>10a</td></tr>
<tr><th>skip me</th></tr>
<tr><td>11</td></tr>
<tr><td>11a</td></tr>
<tr><td>12</td></tr>
<tr><td>12a</td></tr>
</table>

That I would like to stripe with a tr background color.

I am using jQuery and have found a few posts on here and Google relate to the stripping but have failed to find something that skips arbitrary rows.

I have attempted…

$("tr:nth-child(4n)").addClass("alt").prev().addClass("alt");

which works great, but it counts the ones I want to skip.

and

$("tr:not(tr th):nth-child(4n)").addClass("alt").prev().addClass("alt");

with no luck. I even tried to assign a variable to the result of

var trs = $(".classme"); 
$(trs + ":nth-child(4n)").addClass("alt").prev().addClass("alt");

but it still counted applied the style incorrectly.

How do I set a set of selected elements such that the rows I want to exclude are not in the count when the add class is put onto the element?

Edit:
I would like to stripe (in the table example) 1,1a,3,3a,5,5a. So I consider 1 and 1a to be a group. I want to stripe every other group.

Edit:
updated with jsFiddle

Answer 1

Try this:

var rows=   $('.classme:last').nextAll().not(':has(th)');
rows.filter(':even').addClass('evenClass)

Edit .skips lower th tag now

DEMO http://jsfiddle.net/YXDMH/

EDIT: all rows without TH included

var rows=   $('tr').not(':has(th)');
rows.filter(':even').addClass('evenClass').end().filter(':odd').addClass('odd')

http://jsfiddle.net/YXDMH/1/