The Javascript

If your form has radio buttons or other complicated form elements, you should include the jQuery-Forms JS file so that the data is sent to the server in the correct format.

// Set up the list
$('#the-list').wpList(); // Basic Usage.
// or
$('#the-list').wpList( options ); // Advanced Usage.

options = {
	url: '/admin-ajax.php',
		// Where to submit the AJAX request,
	response: 'ajax-response',
		// the HTML id of an element whose innerHTML
		// will be filled with error messages if needed

	what: '',
	alt: 'alternate',
		// the class that will be added to alternate list items.
		// Can be set to blank.
	altOffset: 0, // 0 or 1
		// 0 => odd items will be given alt class
		// 1 => even items
	addColor: null, delColor: null, dimAddColor: null, dimDelColor: null,
		// Fade colors for various actions.
		// Overridden by class parameters in Markup

	confirm: null,
		// Callback function usefupl for Are You Sure?s
		// Called from scope of list element
		// 1st arg: element to delete or dim, or form to add from
		// 2nd: options object
		// 3rd: 'add', 'delete', 'dim' (what we're doing)
		// 4th: original pre-highlight background color of element
		//
		// Return true => "I want to da that", false => "I didn't mean it. Stop."

	addBefore: null, // options.data is a query string
	delBefore: null, // options.data is a JS object
	dimBefore: null, // options.data is a JS object
		// Callback functions executed before AJAX call
		// Accepts options object as first and only parameter
		// options.data is the data that will be sent via AJAX
		//
		// Must return options object (like WP filters must)
		// Can instead return false => AJAX will be aborted,
		//   and "traditional" action will proceed (form submit,
		//   link click...)

	addAfter: null,
	delAfter: null,
	dimAfter: null,
		// Callback function executed after AJAX call succeeds
		// Accepts response(XML|Text) as 1st argument, options object as 2nd
		

};

// Add alt class to appropriate elements
$("#the-list').wpList.recolor();

// Add HTML or element to list manually.  No AJAX involved.  The .get(0) is really important
$("#the-list').get(0).wpList.add( HTML or element );

Server Side

The server should exit with one of the following.

(string) -1

This response indicates that the user does not have permission to perform the requested action. This could be because of the user lacks a capability you're checking for or because the nonce check failed.

(string) 0

Indicates that something reall strange happened. You should only return this when you have no idea what the error really is.

(string) 1

"All is well. The requested action was performed with no problem."

(string) Raw Text or HTML

"Something bad happened; the requested action did not complete. Here is an error message."

XML generated by (object) new WP_Ajax_Response

The client side JS expects the XML to be formatted in a particular way. The WP_Ajax_Response class should be used to generate that XML. You will need to use this method when AJAX adding to a list.

The WP_Ajax_Response Class

// Respond with single item
$x = new WP_Ajax_Response( array(
	'what'  => 'object', // the item "type" of your list
	'action' => false, // (optional) formatted like a nonce action
	'id' => 0, // The unique identifier of the item (not the HTML id)
	'oldId' => 0, // (optional) If you were updating an item, did it formerly have a different id?
	'position' => 1,
		// -1 => insert at beginning of list
		// 0  => if oldId, insert where oldId item was
		// 1  => insert at end of list
		// HTML_ID  => insert after the item with that HTML id
		// -HTML_ID => insert before the item with that HTML id
	'data' => '', // The HTML of the item to be inserted into the list.
	'supplemental' => array()
		// an associative array af extra data to be passed with the XML response:
		// 'supplemental' => array( 'foo' => 'bar' )
		// yields
		// <foo><![CDATA[bar]]></foo>
);
$x->send();

// Respond with several items
$x = new WP_Ajax_Response;
$x->add( ... );
$x->add( ... );
$x->send();

The add: class is given to the whole form.

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