get editarea with jquery

$istanza=rand(1,5000);
include("../ckeditor/ckeditor.php");
$CKEditor = new CKEditor();
$CKEditor->returnOutput = true;
$CKEditor->basePath = '';
$CKEditor->config['width'] = 700;
$CKEditor->textareaAttributes = array("cols" => 120, "rows" => 10);
$config['toolbar'] = array(
   array   ('Source','-','Preview','-','Templates'),
    array ('Cut','Copy','Paste','PasteText','PasteFromWord','-','Print'),
    array ('Undo','Redo','-','Find','Replace','-','SelectAll','RemoveFormat'),
    array ('/'),
    array ('Bold','Italic','Underline','Strike','-','Subscript','Superscript'),
    array ('NumberedList','BulletedList','-','Outdent','Indent','Blockquote'),
    array ('JustifyLeft','JustifyCenter','JustifyRight','JustifyBlock'),
    array ('Link','Unlink','Anchor'),
    array ('Image','Flash','Table','HorizontalRule','Smiley','SpecialChar'),
    array ('/'),
    array ('Styles','Format','Font','FontSize'),
    array ('TextColor','BGColor'),
    array ('Maximize', 'ShowBlocks','-','About')
$initialValue=$resc[post];
   $code = $CKEditor->editor("editor3".$istanza, $initialValue,  $config);
   echo $code;

var testo=$("input[class=<? echo $istanza; ?>]").val();