2. <ul class="nested">
3.   <li class="a-group">4</li>
4.   <li class="a-group">2</li>
5.   <li class="a-group">1</li>
6.   <li class="a-group">3</li>
7.   
8.   <li class="b-group">4</li>
9.   <li class="b-group">2</li>
10.   <li class="b-group">1</li>
11.   <li class="b-group">3</li>
12.   
13.   <li class="c-group">4</li>
14.   <li class="c-group">2</li>
15.   <li class="c-group">1</li>
16.   <li class="c-group">3</li>
17. </ul>

So is there a way I could sort each value within each group, so that I end up with this result:

//Group A

1

2

3

4

So far I only know the simple way of doing this, by sorting without taking each class (group) into account.

Here is a fiddle:  https://jsfiddle.net/nykswcxL/2/