javascript - Ajax and json_encode echoing text instead of json in Firefox -

i have small script returns shipping costs html , php/codeigniter.

here's php code, example data array:

public function atualiza_frete_ajax() {     $response_array = array(        'html_select_frete' => "<form><select><option></option></select></form>"            );                     header("content-type: application/json", true);     echo json_encode($response_array);   } 

and js/jquery

      function atualizar_frete_ajax() {             var $form = $("#form-cep");                 $(".loading").fadein();                 $.ajax({                     type: $form.attr("method"),                     url: $form.attr("action"),                     datatype: "json",                     data: $form.serialize()                     }).done(function(data){                         $(".frete-valor").html(data.html_select_frete)                         $(".loading").hide()                      });                 event.preventdefault();         } 

now issue is: works great in chrome, in firefox nasty text output.

here printscreen of how ff outputs it: http://prntscr.com/5cfcgc

i've made sure file encoding utf8 , no bom, , i'm using correct header before echo response.

any clues?

it's not working because not preventing default behaviour. event.preventdefault() right, need use correctly. if want ajax request @ moment form submitting should use this:

    $(document).on('submit', '#form-cep',function(e)     {         e.preventdefault();         var $form = $(this);             $(".loading").fadein();             $.ajax({                 type: $form.attr("method"),                 url: $form.attr("action"),                 datatype: "json",                 data: $form.serialize()                 }).done(function(data){                     $(".frete-valor").html(data.html_select_frete)                     $(".loading").hide()                  });             }); 

also approuch won't firefox error anymore.

edit

if need function can use this:

function atualizar_frete_ajax()  {     var $form = $("#form-cep");         $(".loading").fadein();         $.ajax({             type: $form.attr("method"),             url: $form.attr("action"),             datatype: "json",             data: $form.serialize()             }).done(function(data){                 $(".frete-valor").html(data.html_select_frete)                 $(".loading").hide()              }); }   $(document).on('submit', '#form-cep',function(e) {     e.preventdefault();     atualizar_frete_ajax();    });