jQuery ajax, send form with input type file and Json -

i have form several inputs , other field.

i have save button, , when click, send form ajax jquery :

$.ajax({         type:       "post",         datatype:   "json",         url:        $('#ajaxurl').val(),         data:       "action=save&" + form.serialize() }); 

so, when have simple input text, select etc.. it's ok. if have input type file, can't retrieve file. $_files empty.

how can possible ?

edit : don't want use plugin :)

implementation asp.net mvc:

to start making form-wrapper :

<form id="inputform">     <input class="hide" type="file" name="file" id="file" /> </form> 

Сreate client-handler send:

$("#yourbutton").bind('click', function () {     var data = new window.formdata($('#inputform')[0]);     $.ajax({         xhr: function () {               return $.ajaxsettings.xhr();         },         type: "post",         data: data,         cache: false,         contenttype: false,         processdata: false,         url: "@url.action("methodname", "controllername")",         success: function () { },         error: function () { },     }); }); 

do handler on server side (controller):

    public actionresult methodname(httppostedfilewrapper file) {     var img = image.fromstream(file.inputstream);        ....        return ..;     } 

i hope save time ;)