Uncaught SyntaxError: Unexpected token :


I am running an AJAX call in my MooTools script, this works fine in Firefox but in Chrome I am getting a Uncaught SyntaxError: Unexpected token : error, I cannot determine why. Commenting out code to determine where the bad code is yields nothing, I am thinking it may be a problem with the JSON being returned. Checking in the console I see the JSON returned is this:

{"votes":47,"totalvotes":90}

I don't see any problems with it, why would this error occur?

vote.each(function(e){
  e.set('send', {
    onRequest : function(){
      spinner.show();
    },
    onComplete : function(){
      spinner.hide();
    },
    onSuccess : function(resp){
      var j = JSON.decode(resp);
      if (!j) return false;
      var restaurant = e.getParent('.restaurant');
      restaurant.getElements('.votes')[0].set('html', j.votes + " vote(s)");
      $$('#restaurants .restaurant').pop().set('html', "Total Votes: " + j.totalvotes);
      buildRestaurantGraphs();
    }
  });

  e.addEvent('submit', function(e){
    e.stop();
    this.send();
  });
});

Seeing red errors

Uncaught SyntaxError: Unexpected token <

in your Chrome developer's console tab is often an indication of 301 Redirects that could be caused by having a strange rule in your .htaccess file.

What you're actually seeing is your browser's reaction to the unexpected top line <!DOCTYPE html> from the server.


Just an FYI for people who might have the same problem -- I just had to make my server send back the JSON as application/json and the default jQuery handler worked fine.


This has just happened to me, and the reason was none of the reasons above. I was using the jQuery command getJSON and adding callback=? to use JSONP (as I needed to go cross-domain), and returning the JSON code {"foo":"bar"} and getting the error.

This is because I should have included the callback data, something like jQuery17209314005577471107_1335958194322({"foo":"bar"})

Here is the PHP code I used to achieve this, which degrades if JSON (without a callback) is used:

$ret['foo'] = "bar";
finish();

function finish() {
    header("content-type:application/json");
    if ($_GET['callback']) {
        print $_GET['callback']."(";
    }
    print json_encode($GLOBALS['ret']);
    if ($_GET['callback']) {
        print ")";
    }
    exit; 
}

Hopefully that will help someone in the future.


I have just solved the problem. There was something causing problems with a standard Request call, so this is the code I used instead:

vote.each(function(element){                
  element.addEvent('submit', function(e){
    e.stop();
    new Request.JSON({
      url : e.target.action, 
      onRequest : function(){
        spinner.show();
      },
      onComplete : function(){
        spinner.hide();
      },
      onSuccess : function(resp){
        var j = resp;
        if (!j) return false;
        var restaurant = element.getParent('.restaurant');
        restaurant.getElements('.votes')[0].set('html', j.votes + " vote(s)");
        $$('#restaurants .restaurant').pop().set('html', "Total Votes: " + j.totalvotes);
        buildRestaurantGraphs();
      }
    }).send(this);
  });
});

If anyone knows why the standard Request object was giving me problems I would love to know.


I thought I'd add my issue and resolution to the list.

I was getting: Uncaught SyntaxError: Unexpected token < and the error was pointing to this line in my ajax success statement:

var total = $.parseJSON(response);

I later found that in addition to the json results, there was HTML being sent with the response because I had an error in my PHP. When you get an error in PHP you can set it to warn you with huge orange tables and those tables were what was throwing off the JSON.

I found that out by just doing a console.log(response) in order to see what was actually being sent. If it's an issue with the JSON data, just try to see if you can do a console.log or some other statement that will allow you to see what is sent and what is received.


When you request your JSON file, server returns JavaScript Content-Type header (text/javascript) instead of JSON (application/json).

According to MooTools docs:

Responses with javascript content-type will be evaluated automatically.

In result MooTools tries to evaluate your JSON as JavaScript, and when you try to evaluate such JSON:

{"votes":47,"totalvotes":90}

as JavaScript, parser treats { and } as a block scope instead of object notation. It is the same as evaluating following "code":

"votes":47,"totalvotes":90

As you can see, : is totally unexpected there.

The solution is to set correct Content-Type header for the JSON file. If you save it with .json extension, your server should do it by itself.


It sounds like your response is being evaluated somehow. This gives the same error in Chrome:

var resp = '{"votes":47,"totalvotes":90}';
eval(resp);

This is due to the braces '{...}' being interpreted by javascript as a code block and not an object literal as one might expect.

I would look at the JSON.decode() function and see if there is an eval in there.

Similar issue here: Eval() = Unexpected token : error


If nothing makes sense, this error can also be caused by PHP Error that is embedded inside html/javascript, such as the one below

<br />
<b>Deprecated</b>:  mysql_connect(): The mysql extension is deprecated and will be removed in the future: use mysqli or PDO instead in <b>C:\Projects\rwp\demo\en\super\ge.php</b> on line <b>54</b><br />
var zNodes =[{ id:1, pId:0, name:"ACE", url: "/ace1.php", target:"_self", open:true}

Not the <br /> etc in the code that are inserted into html by PHP is causing the error. To fix this kind of error (suppress warning), used this code in the start

error_reporting(E_ERROR | E_PARSE);

To view, right click on page, "view source" and then examine complete html to spot this error.


"Uncaught SyntaxError: Unexpected token" error appearance when your data return wrong json format, in some case, you don't know you got wrong json format.
please check it with alert(); function

onSuccess : function(resp){  
   alert(resp);  
}

your message received should be: {"firstName":"John", "lastName":"Doe"}
and then you can use code below

onSuccess : function(resp){  
   var j = JSON.decode(resp); // but in my case i'm using: JSON.parse(resp); 
}

with out error "Uncaught SyntaxError: Unexpected token"
but if you get wrong json format
ex:

...{"firstName":"John", "lastName":"Doe"}

or

Undefined variable: errCapt in .... on line<b>65</b><br/>{"firstName":"John", "lastName":"Doe"}

so that you got wrong json format, please fix it before you JSON.decode or JSON.parse


This happened to me today as well. I was using EF and returning an Entity in response to an AJAX call. The virtual properties on my entity was causing a cyclical dependency error that was not being detected on the server. By adding the [ScriptIgnore] attribute on the virtual properties, the problem was fixed.

Instead of using the ScriptIgnore attribute, it would probably be better to just return a DTO.


This happened to because I have a rule setup in my express server to route any 404 back to /# plus whatever the original request was. Allowing the angular router/js to handle the request. If there's no js route to handle that path, a request to /#/whatever is made to the server, which is just a request for /, the entire webpage.

So for example if I wanted to make a request for /correct/somejsfile.js but I miss typed it to /wrong/somejsfile.js the request is made to the server. That location/file does not exist, so the server responds with a 302 location: /#/wrong/somejsfile.js. The browser happily follows the redirect and the entire webpage is returned. The browser parses the page as js and you get

Uncaught SyntaxError: Unexpected token <

So to help find the offending path/request look for 302 requests.

Hope that helps someone.


I got a "SyntaxError: Unexpected token I" when I used jQuery.getJSON() to try to de-serialize a floating point value of Infinity, encoded as INF, which is illegal in JSON.


In my case i ran into the same error, while running spring mvc application due to wrong mapping in my mvc controller

@RequestMapping(name="/private/updatestatus")

i changed the above mapping to

 @RequestMapping("/private/updatestatus")

or

 @RequestMapping(value="/private/updatestatus",method = RequestMethod.GET)

For me the light bulb went on when I viewed the source to the page inside the Chrome browser. I had an extra bracket in an if statement. You'll immediately see the red circle with a cross in it on the failing line. It's a rather unhelpful error message, because the the Uncaught Syntax Error: Unexpected token makes no reference to a line number when it first appears in the console of Chrome.


For those experiencing this in AngularJs 1.4.6 or similar, my problem was with angular not finding my template because the file at the templateUrl (path) I provided couldn't be found. I just had to provide a reachable path and the problem went away.


In my case it was a mistaken url (not existing), so maybe your 'send' in second line should be other...


I did Wrong in this

   `var  fs = require('fs');
    var fs.writeFileSync(file, configJSON);`

Already I intialized the fs variable.But again i put var in the second line.This one also gives that kind of error...


Uncaught SyntaxError: Unexpected token }

Chrome gaved me the error for this sample code:

<div class="file-square" onclick="window.location = " ?dir=zzz">
    <div class="square-icon"></div>
    <div class="square-text">zzz</div>
</div>

and solved it fixing the onclick to be like

... onclick="window.location = '?dir=zzz'" ...

But the error has nothing to do with the problem..


I had the same problem and it turned out that the Json returned from the server wasn't valid Json-P. If you don't use the call as a crossdomain call use regular Json.


My mistake was forgetting single/double quotation around url in javascript:

so wrong code was:

window.location = https://google.com;

and correct code:

window.location = "https://google.com";

The syntax error is in your success callback. You've named the argument return, which is a reserved word. Call it something else.


Niet here, merging my answer into this one to complete the picture:

Change:

$.ajax(function() {

To:

$.ajax({

Pay closer attention to what you're writing :p


return is a reserved word in JavaScript. Use any other name other than return. I have used data instead of return. Also there is type is an error in ajax function you have written. updated the same. Use the below code

<script type="text/javascript">
$('.delete-btn').click(function() {
 $.ajax({
    type: 'POST',
    url: 'ajax.php',
    data: { filename: filename },
    success: function(data) {
        if(data == 'SUCCESS') {
            $this = $(this).closest('tr');
            $this.remove();
        }
    }
});
});
</script>

return is a keyword at javascript dont use it as a variable name

 <script type="text/javascript">
    $('.delete-btn').click(function() {
     $.ajax(function() {
        type: 'POST',
        url: 'ajax.php',
        data: { filename: filename },
        success: function(data) {
            if(data== 'SUCCESS') {
                $this = $(this).closest('tr');
                $this.remove();
            }
        }
    });
    });
    </script>

You are missing a bracket at the end of "users" property.

{
  "users": [{
      "timestamp": "5/4/2017 8:32:29",
      "name": "Alca",
      "IV": 5,
      "V": 5,
      "VI": 5,
      "I": 2,
      "II": 4,
      "III": 5,
      "VII": 4,
      "Rogue1": 3,
      "Holiday": null
  }], //more code... 
}


 {
    "users"[{
        "timestamp": "5/4/2017 8:32:29",
        "name": "Alca",
        "IV": 5,
        "V": 5,
        "VI": 5,
        "I": 2,
        "II": 4,
        "III": 5,
        "VII": 4,
        "Rogue1": 3,
        "Holiday": null
    },{ "timestamp": "5/4/2017 16:28:05",
        "name": "Leon",
        "IV": 1,
        "V": 1,
        "VI": 1,
        "I": 1,
        "II": 1,
        "III": 1,
        "VII": 1,
        "Rogue1": 1,
        "Holiday": 1
    }]
}

Copy and paste code in this link

i think you should remove ":" behind users it not showing syntax error please check on this link..if any query then tell to me.


the correct json is

{
  "users": [{
      "timestamp": "5/4/2017 8:32:29",
      "name": "Alca",
      "IV": 5,
      "V": 5,
      "VI": 5,
      "I": 2,
      "II": 4,
      "III": 5,
      "VII": 4,
      "Rogue1": 3,
      "Holiday": null
  },{ "timestamp": "5/4/2017 16:28:05",
    "name": "Leon",
    "IV": 1,
    "V": 1,
    "VI": 1,
    "I": 1,
    "II": 1,
    "III": 1,
    "VII": 1,
    "Rogue1": 1,
    "Holiday": 1
}] 
}

You can text JSON Viewer at below link

JSON VIEWER LINK


The use of callback=? is telling jQuery to make a request for JSONP.

The server is responding with JSON (but claiming it is HTML).

JSON is not JSONP so trying to "parse" it as such throws an error.

("parse" is in scare quotes because JSONP isn't so much parsed as executed).


Get rid of the callback=? to try to fetch the data using XMLHttpRequest instead of <script>. Note, however, that unless you are running the script on http://curvefever.com, you will get a cross-origin error since the server is not responding with CORS headers.

Unless you can change the server to return JSONP or to respond with CORS headers, you will need to use a proxy to access the data from client side JavaScript.


I think below code will work

try Using getJSON method of ajax and also try changing "#deatils" to "#details" as i guess you might be mis-spelling the exact name

Hope this helps.