Edit in JSFiddle

<div class="parent">
    <div class="child">1</div>
    <div class="child">2</div>
    <div class="child">3</div>
    <div class="child">4</div>
    <div class="child">5</div>
</div>
<input type="button" id="btn" value="Show DESC">

$('#btn').click(function () {
    if (this.value == 'Show ASC') this.value = 'Show DESC';
    else this.value = 'Show ASC';
    var list = $('div.parent');
    var listItems = list.children('div.child');
    list.append(listItems.get().reverse());
});