<div id="genres">
  <div class="genre">
    <select name="genre[]">
      <option>Your favorite genre...</option>
      <option>Death Metal</option>
      <option>Black Metal</option>
      <option>Speed Metal</option>
    </select>
  </div>
</div>
<a id="add-genre" href="#">Add</a>

document.observe("dom:loaded", function() {
  $("add-genre").observe("click", function(event) {
    event.stop();
    var genres = $("genres"); 
    genres.insert(genres.down(".genre").clone(true));
  });
});

Just click the Add link to add a new the select tag.

Another cool new feature is the Element Storage. You can store any kind of data inside a element, and retrieve it when you need it.

Here an example:

<div id="items">
  <div class="item" id="item-1">
    <h1>Item 1</h1>
    <a href="#" class="save">Save</a>
  </div>
  <div class="item" id="item-2">
    <h1>Item 2</h1>
    <a href="#" class="save">Save</a>
  </div>
</div>

document.observe("dom:loaded", function() {
  var item = $("item-1");
  var data = item.retrieve("data", {});
  data.url = "http://cowboys.from.hell/items/1";			
 
  $("items").select("a.save").invoke("observe", "click", function(event) {
    alert(event.target.up(".item").retrieve("data").url);
  });
});

Just click the first save link and an alert will display the url I previously stored inside the first item element.

Given what I’m seeing I’m pretty excited about the upcoming version of prototype.

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var Pagination = {  

  initLinks: function() {
    $('container').select('div.pagination a').invoke('observe', 'click', Pagination.linkHandler);
  },

  linkHandler: function(event) {
    event.stop();
    new Ajax.Updater('container', event.element().getAttribute('href'),{
      method: 'get',
      onComplete: Pagination.initLinks
    });
  }

}

document.observe('dom:loaded', Pagination.initLinks);

Obviously the code it’s not optimized, it’s just an example, but it works. You only need create a list of records inside a div caled ‘container’, and that div will be update with the content loaded by the ajax request.

[UPDATE] I like the prototype OO way to write js. So I wote the same thing with a class:

var Pagination = Class.create({ 

  initialize: function() {
    this.options = Object.extend({
      container: 'container'
    }, arguments[0] || {});
    this.initLinks();
  },  

  initLinks: function() {
    $(this.options.container).select('div.pagination a').invoke('observe', 'click', this.linkHandler.bind(this));
  },  

  linkHandler: function(event) {
    event.stop();
    new Ajax.Updater('container', event.element().getAttribute('href'),{
      method: 'get',
      onComplete: this.initLinks.bind(this)
    });
  }

});

document.observe('dom:loaded', function() {
  new Pagination();
});

The latest version is more customizable because the constructor could receive a list of options. For now it’s only one, you can specify the container that will be updated, but you could add more options like the name of the spinner to show during requests and so on.

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function sort(list, element, id, old_position, new_position) {
  new Ajax.Request('/admin/gallery_item/sort/', {
    evalScripts:true,
    parameters: {
      id: id,
      old_position: old_position,
      new_position: new_position
    }
  });
}

document.observe('dom:loaded', function() {
  new LiteSortable('list', {
    onUpdate: sort
  });
});

And the server code become like the following:

def sort
  old_position, new_position = params[:old_position].to_i, params[:new_position].to_i
  @item = GalleryItem.find(:first, :conditions => ["id = ? AND position = ?", params[:id], old_position])
  if @item
    x, y, z = old_position < new_position ? ["-", "<", ">"] : ["+", ">", "<"]
    GalleryItem.update_all("position = (position #{x} 1)", ["parent_id IS NULL AND gallery_id = ? AND position #{y}= ? AND position #{z}= ?", @item.gallery_id, new_position, old_position])
    @item.update_attribute('position', new_position)
  else
    @error = true
  end
end

If @error is true, it means that the dragged image it’s been deleted or moved by somone else.
If you want to use LiteSortable you can check out the entire project with:

svn co http://dev.gravityblast.com/svn/projects/js/LiteSortable/

…or save download the lite_sortable.js file from here.

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