[Sweet]

Логика примерно такая:

<div id="container">
  <div class="item">
    <div class="num">22</div>
  </div>
  <div class="item">
    <div class="num">5</div>
  </div>
  <div class="item">
    <div class="num">18</div>
  </div>
  <div class="item">
    <div class="num">37</div>
  </div>
  <div class="item">
    <div class="num">2</div>
  </div>
</div>

<script>

var divs = Array.prototype.slice.call(document.querySelectorAll('#container .item'));

divs.sort(sort);
divs.forEach(putIn, container);


function sort(a, b) {
  return getValue(a) > getValue(b);
  
  function getValue(element) {
    return Number(element.querySelector(".num").textContent);
  }
}

function putIn(item) {
  this.appendChild(item);
}

</script>