javascript - ajax - sending data as json to php server and receiving response -

i'm trying grasp more should @ once.

let's have 2 inputs , button, , on button click want create json containing data inputs , send server.

i think should it, might wrong i've seen lot of different (poorly explained) methods of doing similar.

    var item = function(first, second) {         return {             firstpart : first.val(),              secondpart : second.val(),          };     };      $(document).ready(function(){         $("#send_item").click(function() {             var form = $("#add_item");              if (form) {                 item = item($("#first"), $("#second"));                  $.ajax ({                     type: "post",                     url: "post.php",                      data: { 'test' : item },                     success: function(result) {                         console.log(result);                     }                 });             }         });     }); 

in php have

class clientdata {     public $first;     public $second;      public function __construct($f, $s)     {         $this->first = f;         $this->second = s;     } }  if (isset($_post['test'])) {     // stuff, object of type clientdata } 

the problem $_post['test'] appears array (if pass json_decode error says array , if iterate using foreach values expect see). ajax call correct? there else should in php bit?

for sending raw form data:
js part:

$.ajax ({     type: "post",     url: "post.php",      data: item ,     success: function(result) {         console.log(result);     } }); 

php part:

.. if (isset($_post['firstpart']) && isset($_post['secondpart'])) {     $fpart = $_post['firstpart'];     $spart = $_post['secondpart'];     $obj = new clientdata($fpart, $spart); } ... 

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for sending json string:
js part:

$.ajax ({     type: "post",     url: "post.php",      data: {'test': json.stringify(item)},     success: function(result) {         console.log(result);     } }); 

php part:

..  if (isset($_post['test'])) {     $json_data = $_post['test'];     $json_arr = json_decode($json_data, true);     $fpart = $json_arr['firstpart'];     $spart = $json_arr['secondpart'];     $obj = new clientdata($fpart, $spart); } ...