通过Cakephp中的ajax发送数据

i am new to cakephp and trying to send data from ajax to my controller action.. i have a popup model in which there is a input box ..i want to grab that value and send to controller without page refresh

here is my code ..

 <a  class="button anthracite-gradient" onclick="openPrompt()">submit </a>

my javascript

 function openPrompt()
{
var cancelled = true;

$.modal.prompt('Please enter a value:', function(value)
{

    $.ajax({
        type:"POST",

        url:"/cakephp/controller/action/",
        success : function(data) {
           alert(value); //value right now is in this variable ... i want to send this variable value to the controller

        },
        error : function() {
           alert("false");
        }
    });


    }, function()
   {

    });
    };
</script>

myController

 public function action(){
    if( $this->request->is('ajax') ) {
      $new = $this->request->data; 

        echo "ok"
        return;
    }
}

i want to first get the value here and then send the response to may ajax request