function randomBox(randomItem) {

  randomItem = $(randomItem);

  var random = Math.floor(Math.random() * randomItem.length);

  randomItem.eq(random % randomItem.length).addClass('active');

  function startRand() {

    var current = randomItem.parent().find('.active');

    if ( current.is(':last-child') ) {
      current.removeClass('active');
      current.siblings(':first-child').addClass('active');
    } else {
      current.removeClass('active');
      current.next().addClass('active');
    }

    setTimeout(function(){startRand()}, 2500);
  }

  startRand();
}

randomBox('.list > .item');