SyntaxError: JSON.parse: unexpected character

Question

I have a JSON parse error that I can't debug. Code below:

$(document).on('submit', '#confirmreset', function(event) {
    event.preventDefault();

    var action_url = $(this).attr("action");
    alert_box_register("Resetting password...");
    console.log(action_url);
    var postData = $(this).serializeArray();
    console.log(postData);

    $.post(action_url, postData, function(data) {
        console.log(data);
        var obj = $.parseJSON(data);

        alert_box_register(obj.message);
    });
});

And the JSON:

{
    "status": "success",
    "message": "A temporary password has been emailed to you."
}

In Firefox the error is "SyntaxError: JSON.parse: unexpected character", in Chrome it's "Uncaught SyntaxError: Unexpected token C "

Any ideas?

*EDIT: This works fine on my localhost setup. *

That is valid JSON *as presented*, so I suspect that the *real* JSON data contains a character that is not making it across the translation. — user2864740, Nov 06 '13 at 22:32
it happens within `$.parseJSON(data)`, but i'm sure you knew that. — Kevin B, Nov 06 '13 at 22:37
Don't parse the json inside the callback. Instead, tell jquery that it is json. `$.post(action_url, postData, function(data){...}, "json")` If your success stops working, that means your server isn't returning valid json. — Kevin B, Nov 06 '13 at 22:38
@ExplosionPills I assume that's jQuery formatting? This error is caught in jquery.min — alias51, Nov 06 '13 at 22:42
@JasonP It's processed through a PHP script (http://www.php-login.net MVC v4 to be precise) — alias51, Nov 06 '13 at 22:44

score 18 · Accepted Answer · answered Nov 06 '13 at 22:46

18

You don't need to call $.parseJSON if the server is sending valid JSON as jQuery will parse it automatically when it retrieves the response. I don't know the exact criteria, but if you set the Content-type: application/json header it definitely will.

answered Nov 06 '13 at 22:46

Explosion Pills

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Thanks, so would you propose just 'var obj = $(data);' – alias51 Nov 06 '13 at 22:47
No, just `var obj = data`, or even `function (obj) {` -- basically `data` is ready for use immediately – Explosion Pills Nov 06 '13 at 22:49
This creates Object {status: "error", message: Array[1]} (index):241 Uncaught SyntaxError: Unexpected token o – alias51 Nov 06 '13 at 22:52
@alias51 that means your server isn't returning valid json. – Kevin B Nov 06 '13 at 22:55
@KevinB Ok, thanks but when I lint the JSON in the question, it returns as valid? – alias51 Nov 06 '13 at 22:57
Right, but that's probably not the only thing the server is returning. – Kevin B Nov 06 '13 at 22:57
...so how would I debug this properly? – alias51 Nov 06 '13 at 23:00
@KevinB (fyi, this works fine on a localhost server, which is odd) – alias51 Nov 06 '13 at 23:01
1

Thanks. Was looking for answer, and this proved to be my problem as well. Trying to parse already parsed data. Since it is pre-paresed when usning json as type or getJSON as method. – Björn3 Dec 22 '13 at 10:33

score 1 · Answer 2 · answered Jan 15 '20 at 10:13

1

This error can be caused by using single quotation marks (') instead of double (") for strings.

The JSON spec requires double quotation marks for strings.

SyntaxError: JSON.parse: unexpected character

3 Answers3

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