jQuery Ajax - Cant parse json? - ajax

Question

I got a very strange problem, I thought this worked before but it doesn't any more. I dont even remember changing anything. I tried with an older jQuery library.
I got an error that says: http://i.imgur.com/H51wG4G.png on row 68: (anonymous function). which refer to row 68:
var jsondata = $.parseJSON(data);
This is my ajax function
I can't get my alert to work either because of this error. this script by the way is for logging in, so if I refresh my website I will be logged in, so that work. I also return my json object good as you can see in the image. {"success":false,"msg":"Fel anv\u00e4ndarnamn eller l\u00f6senord.","redirect":""}
When I got this, I will check in login.success if I got success == true and get the login panel from logged-in.php.
$('#login_form').submit(function()
{
var login = $.ajax(
{
url: '/dev/ajax/trylogin.php',
data: $(this).serialize(),
type: 'POST',
}, 'json');
login.success(function(data)
{
var jsondata = $.parseJSON(data);
console.log(jsondata);
if(jsondata.success == true)
{
$.get("/dev/class/UI/logged-in.php", function(data) {
$(".login-form").replaceWith(data);
});
}
else
{
alert(jsondata.msg);
$('#pwd').val('');
}
});
return false;
});
Thank you.

Answer 1

If the response you have showed in the attached screenshot is something to go by, you have a problem in your PHP script that's generating the JSON response. Make sure that thePHP script that's generating this response (or any other script included in that file) is not using a constant named SITE_TITLE. If any of those PHP files need to use that constant, make sure that that SITE_TILE is defined somewhere and included in those files.
What might have happened is that one of the PHP files involved in the JSON response generation might have changed somehow and started using the SITE_TITLE costant without defining it first, or without including the file that contains that constant.
Or, maybe none of the files involved in the JSON generation have changed, but rather, your error_reporting settings might have changed and now that PHP interpreter is outputting the notice level texts when it sees some undefined constant.
Solving the problem
If the SITE_TITLE constant is undefined, define it.
If the SITE_TITLE constant is defined in some other file, include that file in the PHP script that's generating the response.
Otherwise, and I am not recommending this, set up your error_reporting settings to ignore the Notice.

Answer 2

Your response is not a valid JSON. You see: "unexpected token <".
It means that your response contains an unexpected "<" and it cannot be converted into JSON format.
Put a console.log(data) before converting it into JSON.

Answer 3

You shoud use login.done() , not login.success() :)
Success is used inside the ajax() funciton only! The success object function is deprecated, you can set success only as Ajax() param!
And there is no need to Parse the data because its in Json format already!
jQuery Ajax
$('#login_form').submit(function()
{
var login = $.ajax(
{
url: '/dev/ajax/trylogin.php',
data: $(this).serialize(),
type: 'POST',
}, 'json');
login.done(function(data)
{
var jsondata = data;
console.log(jsondata);
if(jsondata.success == true)
{
$.get("/dev/class/UI/logged-in.php", function(data) {
$(".login-form").replaceWith(data);
});
}
else
{
alert(jsondata.msg);
$('#pwd').val('');
}
});
return false;
});