Jquery Nth-Child question

Question

Hey Guys,

How, using Nth-Child could I add a class to every red box?

I have tried using:

$('#mainnav li ul li:nth-child(3n)').addClass('yes');

Markup:

<ul>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
      <li><a href="">SUUB</a></li>
</ul>

Answer 1

This one will put the yes class on all LIs, except for the first one and then every third:

$('#mainnav li ul li:not(:nth-child(3n+1))').addClass('yes');

Answer 2

As one solution, you can apply the class to all items and remove it from every third...

$('#mainnav ul li').addClass('yes').parent().find(':nth-child(3n)').removeClass('yes');​​​​