JS to change Z-indexes with an interval

I have a <div> with an <ul> with several <li> items in it. <div> has a class, <ul> seperate class and <li> seperate class and ID. Now I need a piece of JS that 1. changes the z-index of <li> #id1 to 1 2. waits 15 sec 3. changes the z-index of <li> #id1 to 0 and of <li> #id2 to 1 4. continues for all the <li> items and starts at 1 again when all have been done, <div class="divClass"> <ul class="ulClass"> <li id="id1" class="liClass"> <h1>Title 1</h1> <p>Lorem ipsum dolor sit amet 1</p> </li> <li id="id2" class="liClass"> <h1>Title 2</h1> <p>Lorem ipsum dolor sit amet 2</p> </li> </ul> </div> CSS: .divClass { position: relative; } .ulClass { list-style: none; } .liClass { position: absolute; background-color: white; z-index: 0; }