Lo siguiente usa jQuery UI Autocomplete, que se ha incluido en WordPress desde 3.3. (He tomado prestado el formato de @Rarst : D).
Todavía no es precisamente lo que buscas, pero te da un buen punto de partida. Lo siguiente usa un estilo básico de jQuery UI, pero puede usar el que actualmente funciona en trac y llamarlo desde su carpeta de complementos.
class AutoComplete {
static $action = 'my_autocomplete';//Name of the action - should be unique to your plugin.
static function load() {
add_action( 'init', array( __CLASS__, 'init'));
}
static function init() {
//Register style - you can create your own jQuery UI theme and store it in the plug-in folder
wp_register_style('my-jquery-ui','http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css');
add_action( 'get_search_form', array( __CLASS__, 'get_search_form' ) );
add_action( 'wp_print_footer_scripts', array( __CLASS__, 'print_footer_scripts' ), 11 );
add_action( 'wp_ajax_'.self::$action, array( __CLASS__, 'autocomplete_suggestions' ) );
add_action( 'wp_ajax_nopriv_'.self::$action, array( __CLASS__, 'autocomplete_suggestions' ) );
}
static function get_search_form( $form ) {
wp_enqueue_script( 'jquery-ui-autocomplete' );
wp_enqueue_style('my-jquery-ui');
return $form;
}
static function print_footer_scripts() {
?>
<script type="text/javascript">
jQuery(document).ready(function ($){
var ajaxurl = '<?php echo admin_url( 'admin-ajax.php' ); ?>';
var ajaxaction = '<?php echo self::$action ?>';
$("#secondary #searchform #s").autocomplete({
delay: 0,
minLength: 0,
source: function(req, response){
$.getJSON(ajaxurl+'?callback=?&action='+ajaxaction, req, response);
},
select: function(event, ui) {
window.location.href=ui.item.link;
},
});
});
</script><?php
}
static function autocomplete_suggestions() {
$posts = get_posts( array(
's' => trim( esc_attr( strip_tags( $_REQUEST['term'] ) ) ),
) );
$suggestions=array();
global $post;
foreach ($posts as $post):
setup_postdata($post);
$suggestion = array();
$suggestion['label'] = esc_html($post->post_title);
$suggestion['link'] = get_permalink();
$suggestions[]= $suggestion;
endforeach;
$response = $_GET["callback"] . "(" . json_encode($suggestions) . ")";
echo $response;
exit;
}
}
AutoComplete::load();