问单击单选按钮时的ajax

EN

    $(".product").on('change', function(){ 
    var policy= "gggggggggggg";
    var base_url = window.location.origin;
//alert(policy);
  $.ajax( {
  type: "POST",
  url: base_url+"/sales/index.php/Add_AMC/Insurance_chg",
  data: policy,
  success: function( response ) {
    alert(response);
  }
});
});

//Add_amc.php controller
//function Insurance_chg(){
        $product=$_POST['policy'];
        echo $product;die();
    }