function ajax_search()
{
    global $wp_query;
    header('Content-type:application/json; Charset=utf-8');
    $text   = !empty($_POST['text']) ? esc_sql($_POST['text']) : null;
    $args = array('s' => $text,'posts_per_page' => 8);
    $array_posts = array ();
    $data = new WP_Query($args);
    while ( $data->have_posts() ) : $data->the_post();
        array_push($array_posts, array("title"=>get_the_title(),"url"=>get_permalink(),"img"=>_get_post_timthumb_src() )); 
    endwhile;
    echo json_encode($array_posts);
    exit();
}