AJAX第二次不会获得JSON数据

Question

I'm sending Ajax request to a php file, that file returns an JSON array of the submitted data, the first time is great, it sends the data and gets it, so i can use it, but second time it gives me an error

SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data

My goal is to validate the data in the php file, if the data is not validated then i'm adding an error classes to the fields that are not validated, then the user correct those fields, and sends the form again, without refreshing.

My testing shows that its working for the first time, but when i want to send the form the second time, it gives me the above error, any clues what it can be?

AJAX :

$('#ajax').submit('submit', function(){

var that = $(this),
url = that.attr('action'),
type = that.attr('method'),
data = {};

that.find('[name]').each(function(index, value){
    var that = $(this),
    name = that.attr('name'),
    value = that.val();

    data[name] = value;
});

$.ajax({
    url: url,
    type: type,
    data: data,
    cache:false,

    success: function(response){
        var json = response,
        obj = JSON.parse(json);
        if(obj.title == 'Mrs.'){
        //  $('#title').addClass('has-warning');
            $(function () {
              $('#name').tooltip({ 'title': 'Please fill name'});
            });
        }
        alert(obj.title);
    }

});
return false;
});

PHP file:

if(Input::exists()){
if(token::check(Input::get('token'))){

    echo json_encode(
    array(
        "title" => Input::get('title')
        )
    );
}

}

Answer 1

Your token check is the culprit here. It's not working the second time because it's returning an empty response. This is because you probably need to recreate a new Token and send it with the first response. To test if this is the issue, just write :

if(Input::exists()){
 if(token::check(Input::get('token'))){

  echo json_encode(
  array(
    "title" => Input::get('title')
    )
  );
 }else{
   echo json_encode(
     array("title" => 'See? You need to update token')
   );
 }
}

You should regenerate a new Token and then update it's value in the form :

echo json_encode(
     array("newToken" => Token::generate() )
   );