Javascript DOM List Swap Nodes Example

I couldn’t find an easy to follow example to do this anywhere on the web so I did my own up. Basically I wanted a list where each item has an up and a down button that will dynamically reorder the list. I tried swapping the nodes themselves but it didn’t work so it seems that I have to use the removeChild and insertBefore methods to actually see the results on the page.
Here is the Javascript DOM Example


<ul id='list' name='list'>
</ul>

<script type='text/javascript'>

//swap the current li node with the one above it
function up(button_node)
{
  var current_node = button_node.parentNode;
  var list_children = document.getElementById('list').childNodes;
  var list_node = document.getElementById('list');
  
  var temp_node;
  var previous_node;
  
  for(var i=0;i<list_children.length;i++)
  {
    if(current_node.id == list_children[i].id && previous_node)
    {
      temp_node = list_children[i].cloneNode(true);
      list_node.removeChild(list_children[i]);
      list_node.insertBefore(temp_node,previous_node);
    }
    if(list_children[i].tagName=='LI')
      previous_node=list_children[i];
  }
}

//swap the chosen li node with the one below it
function down(button_node)
{
  var current_node = button_node.parentNode;
  var list_children = document.getElementById('list').childNodes;
  var list_node = document.getElementById('list');
  
  var temp_node;
  var previous_node = "";
  
  for(var i=0;i<list_children.length;i++)
  {
    if(current_node.id == list_children[i].id)
    {
      previous_node=list_children[i];  
    }
    else if(previous_node && list_children[i].tagName=='LI')
    {
      temp_node = list_children[i].cloneNode(true);
      list_node.removeChild(list_children[i]);
      list_node.insertBefore(temp_node,previous_node);
      previous_node = "";
    }
  }
}

//create the li elements
function create_list()
{
  for(var i=0;i<6;i++)
  {
    add_li('list', "Item "+i," Item "+(i+1)+" \
    <input type='button' id='up_button1' value='Up' onclick='up(this);'>\
    <input type='button' id='down_button1' value='Down' onclick='down(this);'>");
  }  
}

//add a li element
function add_li(list, id, text) {
  var list = document.getElementById(list);
  var li = document.createElement("li");
  li.innerHTML = text;
  li.id=id;
  list.appendChild(li);
}

create_list();
</script>

So it is a little longer than I expected but it works and it’s pretty easy to understand.

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