Я просто изменяю это
$('#submit').click(function(){
var message_options = $('textarea').val(); // I change the element id to textarea. I dont know why if I use ID does not working. Thank you
$.ajax({
type: "post",
url: ajax_params.ajax_url,
data: {"action": "data",
"message_options":message_options,
},
success: function(data){
}
});
});