different classes to list (i 3)
<p>im having a huge div with a grid inside, 30 items in 3 columns. but i have to add some classes to show them in the right way. like adding prefix_1 for the first one, prefix_2 for the second and 3th. also a alpha and a omega class. like you can see below.</p>

<p>im doing it with jquery at the moment, but thats very slow.</p>

<p>can someone help me to improve the jquery code?
or tell me how to do it in css, and that it will still work in ie7/ie8</p>

<pre><code>for(var i=0;i&lt;30;i+3)
{
    $('.docs').eq(i).addClass('prefix_1');
}

for(var i=1;i&lt;30;i+3)
{
    $('.docs').eq(i).addClass('prefix_2').addClass('alpha');
}

for(var i=2;i&lt;30;i+3)
{
    $('.docs').eq(i).addClass('prefix_2').addClass('omega');
}
</code></pre>
