jQuery .getJSON Firefox 3 Syntax Error Undefined

Question

I'm getting a syntax error (undefined line 1 test.js) in Firefox 3 when I run this code. The alert works properly (it displays 'work') but I have no idea why I am receiving the syntax error.

jQuery code:

$.getJSON("json/test.js", function(data) {
    alert(data[0].test);
});

test.js:

[{"test": "work"}]

Any ideas? I'm working on this for a larger .js file but I've narrowed it down to this code. What's crazy is if I replace the local file with a remote path there is no syntax error (here's an example):

http://api.flickr.com/services/feeds/photos_public.gne?tags=cat&tagmode=any&format=json&jsoncallback=?

Answer 1

Try renaming "test.js" to "test.json", which is what Wikipedia says is the official extension for JSON files. Maybe it's being processed as Javascript at some point.

Answer 2

Have you tried disabling all the Firefox extensions?

I usually get some errors in the Firebug console that are caused by the extensions, not by the webs being visited.

Answer 3

This may sound really really dumb, but change the file extension for test.js from .js to .txt. I had the same thing happen with perfectly valid JSON data files with pretty well any extension except .txt (example: .json, .i18n). Since I've changed the extension, I get the data and use it just fine.

Like I said, it may sound dumb but it worked for me.

Answer 4

The first answer is wrong: Both the following are valid JSON.

{"test":"work"}    
[{"test": "work"}]

The first one is a object (record/struct), the second is an array containing only one value (namely the object above).

I have the same problem as the original author and I am still seeking for the reason. As he note, everything keeps working - only the syntax error is logged. Even more: There is no way to tell where this syntax error happened...

Answer 5

Is anyone having an answere on that issue? I'm currently experiencing the very same error. Is there something I can do?

I thought it might have to do with the wrong MIME-Type beeing send, but I have no proof for it...

Answer 6

Check if there's ; at the end of the test.js. jQuery executes eval("(" + data + ")") and semicolon would prevent Firefox from finding closing parenthesis. And there might be some other unseen characters that prevents it from doing so.

I can tell you why this remote location working though, it's because it's executed in completely different manner. Since it has jsoncallback=? as the part of query parameters, jQuery thinks of it as of JSONP and actually inserts it into the DOM inside <script> tags. Try use "json/test.js?callback=?" as target, it might help too.

Answer 7

What kind of webserver are you running that on? I once had an issue reading a JSON file on IIS because it wasn't defined as a valid MIME type.

Answer 8

I found a solution to kick that error

$.ajaxSetup({'beforeSend': function(xhr){
    if (xhr.overrideMimeType)
        xhr.overrideMimeType("text/plain");
    }
});

Now the explanation: In firefox 3 (and I asume only firefox THREE) every file that has the mime-type of "text/xml" is parsed and syntax-checked. If you start your JSON with an "[" it will raise an Syntax Error, if it starts with "{" it's an "Malformed Error" (my translation for "nicht wohlgeformt"). If I access my json-file from an local script - no server is included in this progress - I have to override the mime-type... Maybe you set your MIME-Type for that very file wrong...

How ever, adding this little piece of code will save you from an error-message

Answer 9

Try configuring the content type of the .js file. Firefox expects it to be text/plain, apparently. You can do that as Peter Hoffmann does above, or you can set the content type header server side.

This might mean a server-side configuration change (like apache's mime.types file), or if the json is served from a script, setting the content-type header in the script.

Or at least that seems to have made the error go away for me.

Answer 10

I had a similar problem but was looping through a for loop. I think the problem might be that the index is out of bound.

• Kien

Answer 11

HI

I have this same error when testing the web page on my local PC, but once it is up on the hosting server the error no longer happens. Sorry - I have no idea of the reason, but thought it may help someone else track down the reason

Answer 12

getJSON may be insisting on at least one name:value pair.
A straight array ["item0","item1","Item2"] is valid JSON, but there's nothing to reference it with in the callback function for getJSON.

In this little array of Zip codes:

{"result":[["43001","ALEXANDRIA"],["43002","AMLIN"],["43003","ASHLEY"],["43004","BLACKLICK"],["43005","BLADENSBURG"],["43006","BRINKHAVEN"]]}

... I was stuck until I added the {"result": tag. Afterward I could reference it:

$.getJSON("temp_test_json.php","", function(data) { $.each(data.result, function(i, item) { alert(item[0]+ " " + i); if (i > 4 ) return false; }); });

... I also found it was just easier to use $.each().