jQuery AJAX JSONP error “Unexpected token”

Question

I'm trying to make a cross domain JSONP call in Chrome, but the I keep getting back "Uncaught SyntaxError: Unexpected token :" I've tried: changing the response content type, setting xhr headers, JSON.stringify, just about most of the solutions offered on here but nothing worked so far :-(

 $.ajax({
                type: "POST",
                url: "https://www.virustotal.com/vtapi/v2/url/report",
                crossDomain: true,
                contentType: "application/json; charset=UTF-8",
                dataType: 'jsonp',
                data: {
                    apikey: "*",
                    resource: "http://www.1001freefonts.com/font/BaroqueScript.zip"
                },
                jsonp: false,
                jsonpCallback: receive,
                success: function (data, textStatus, jqXHR) {
                    console.log("Data retrieved: " + data);
                }
            }).done(function () {
                console.log('I think we are done here');
            })
        .error(function (e) {
            console.log(arguments);
            console.log('something went funny here');
        })
        .complete(function (xhr, status) {

            console.log("complete");
        if (status === 'error' || !xhr.responseText) {
            console.log('error');
        }
        else {
            console.log("data found:" + xhr.responseText);
            //...
        }
    });
    });

    function receive(saveData) {
        if (saveData == null) {
            console.log("DATA IS UNDEFINED!");  // displays every time
        }
        console.log("Success is " + saveData);  // 'Success is undefined'
    }

In the debugger I can see the response

{"permalink": "https://www.virustotal.com/url/b5b546fdbb49a2258e951c5e568a52655c65ac56112e39d15af0954a53b36772/analysis/1360339512/", "url": "http://www.1001freefonts.com/font/BaroqueScript.zip", "response_code": 1, "scan_date": "2013-02-08 16:05:12", "scan_id": "b5b546fdbb49a2258e951c5e568a52655c65ac56112e39d15af0954a53b36772-1360339512", "verbose_msg": "Scan finished, scan information embedded in this object", "filescan_id": "b7e13c0242e9690aba1f3da4b73d9c2e99a9b7fd03f542b55e694a34aaf9eca8-1360339519", "positives": 0, "total": 35, "scans": {"CLEAN MX": {"detected": false, "result": "clean site"}, "MalwarePatrol": {"detected": false, "result": "clean site"}, "ZDB Zeus": {"detected": false, "result": "clean site"}, "K7AntiVirus": {"detected": false, "result": "clean site"}, "Quttera": {"detected": false, "result": "clean site"}, "Yandex Safebrowsing": {"detected": false, "result": "clean site"}, "MalwareDomainList": {"detected": false, "result": "clean site"}, "ZeusTracker": {"detected": false, "result": "clean site"}, "zvelo": {"detected": false, "result": "clean site"}, "Google Safebrowsing": {"detected": false, "result": "clean site"}, "BitDefender": {"detected": false, "result": "clean site"}, "Opera": {"detected": false, "result": "clean site"}, "G-Data": {"detected": false, "result": "clean site"}, "C-SIRT": {"detected": false, "result": "clean site"}, "Sucuri SiteCheck": {"detected": false, "result": "clean site"}, "VX Vault": {"detected": false, "result": "clean site"}, "ADMINUSLabs": {"detected": false, "result": "clean site"}, "SCUMWARE.org": {"detected": false, "result": "clean site"}, "Dr.Web": {"detected": false, "result": "clean site"}, "AlienVault": {"detected": false, "result": "clean site"}, "Malc0de Database": {"detected": false, "result": "clean site"}, "SpyEyeTracker": {"detected": false, "result": "clean site"}, "Phishtank": {"detected": false, "result": "clean site"}, "Avira": {"detected": false, "result": "clean site"}, "Antiy-AVL": {"detected": false, "result": "clean site"}, "Comodo Site Inspector": {"detected": false, "result": "clean site"}, "Malekal": {"detected": false, "result": "clean site"}, "ESET": {"detected": false, "result": "clean site"}, "SecureBrain": {"detected": false, "result": "unrated site"}, "Netcraft": {"detected": false, "result": "clean site"}, "ParetoLogic": {"detected": false, "result": "clean site"}, "URLQuery": {"detected": false, "result": "unrated site"}, "Wepawet": {"detected": false, "result": "unrated site"}, "Minotaur": {"detected": false, "result": "clean site"}}}

I've verified it on http://jsonlint.com/ and it shows that it's a valid JSON.

Here are the Response Headers

cache-control:no-cache
content-encoding:gzip
content-length:695
content-type:application/json
date:Wed, 13 Feb 2013 12:00:33 GMT
server:Google Frontend
status:200 OK
vary:Accept-Encoding
version:HTTP/1.1

Anyone have any ideas/suggestions?

Answer 1

After thorough testing, it was evident that it's not possible to capture the JSON object results when ajax is expecting JSONP in return (due to cross-domain restrictions). Even though the response status = 200.

I've been testing using jQuery AJAX calls, in attempt to see if the result can still be captured - despite there's Parsing Error thrown by the browser - but it didn't seem that's possible. It looks like that the Response Text arrives in the header after JS work is completed.

As @Florian F. @Likwid_T @Christoph have suggested above, a server-side script is definitely required to make it working properly. Other developers seem to be keen on using a proxy written in C# as a solution.

Answer 2

JSONP doesn't work out of the box.

JSONP bypasses the cross-domain restriction by loading the result in a script tag.

Basically, your server has to be JSONP-enabled.

Do whatever needs to be done on your server side then right before sending the response :

1. Check if the request has "_callback" set
2. If set, wrap your content with the value of _callback.
3. Send your data

Code example in PHP :

$responseString = '{"smthing":"val","smthingelse":"val2"}';
if (isset($_REQUEST['_callback'])) {
    $responseString = $_REQUEST['_callback'] . '(' . $responseString . ');';
}

It'll execute your 'done' anonymous function with the right arguments. (JQuery handles everything else)

Answer 3

Christoph is right you need to encase your answer in your callback function, in your case at the end of the PHP file:

echo $_GET['receive'] . '(' . json_encode($yourResultObject) . ');';

or if you need a more complex object

echo $_GET['receive'] . '(' . json_encode(array(name1 => object1, name2 => object2, name3 => object3)) . ');';

You might have to tweak a bit, but basically whenever I get Unexpected token is almost always a syntax error that makes jQuery not get my callback function.