Caching functions of the DOM is a very bad idea as it depends on the browser implementation, so portability is low.

What must be cached is DOM data objects:

function IterateWorkOverCollection()
{
      var target = document.getElementById("target");
      var length = myCollection.getItemCount();

      for(var index = 0; index<length; index++)
      {
            target.appendChild(myCollection[index]);
      }
}

I wonder also about the performance of nextSibling instead of accessing to an element by index.

Olivier Mengu

Caching functions of the DOM is a very bad idea as it depends on the browser implementation, so portability is low.

Very true, "caching" the DOM objects rather then the Objects methods is also a modular approach. If you wanted to use multiple methods/properties of the DOM object, they are a single method/property away. Caching a method limits you to just the use of that single reference.