Parsing JSON data in javascript

Question

I have encountered a bizarre case when attempting to parse some JSON data sent from a server.

The data is essentially, a set of rows of data - i.e. a list of lists, and looks something like this:

[[1,2,3],[4,5,6],[7,8,9]]

In FF (using Firebug), the received JSON data is valid, and renders correctly.

When I attempt to parse the JSON data using either of this statements, it fails:

JSON.parse() code breaks on error
jQuery.parseJSON() parses without complaining, yet the result of the parse is a null object

The only way I have managed to successfully parse the JSON response, is to use the dreaded eval() statements, which is a BIG security issue.

Anyone knows what may be going on?

Testing it in Firebug gives no problems: >>> JSON.parse("[[1,2,3],[4,5,6],[7,8,9]]"); [[1, 2, 3], [4, 5, 6], [7, 8, 9]]. I suspect that you have over-reduced your reduced test case. — Quentin
– Quentin, Commented Feb 11, 2011 at 7:32
What does jslint say? Did you check whitespace? Any invalid (invisible) characters? Encoding OK? — Konerak
– Konerak, Commented Feb 11, 2011 at 7:35
$.parseJSON() actually uses eval() after cleaning checking the JSON string with regex. — Luca Matteis
– Luca Matteis, Commented Feb 11, 2011 at 8:48
why don't you use eval('(' + dataString + ')') what is the security issue for that. I've used this method every time, and it works fine — Fatih Acet
– Fatih Acet, Commented Feb 11, 2011 at 8:54
I found the solution. It seems that when the server responds with a content type of text/json, the string is automatially parsed by jQuery into a JSO object, so I was ineffect trying to parse twice - hence the error. — skyeagle
– skyeagle, Commented Feb 12, 2011 at 12:29

trzewiczek · Accepted Answer · 2011-02-11 07:35:21Z

0

I'm just starting my adventure with JavaScript and JSON, but it looks like it's not a valid JSON object. There is no key:value in this list of lists. I wold suggest changing it into list of obects containing list fields. Sth like:

[ 
{ list: [ 1, 2, 3 ] },
{ list: [ 1, 2, 3 ] },
{ list: [ 1, 2, 3 ] }
]

But I might be very wrong.

answered Feb 11, 2011 at 7:35

trzewiczek

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3 Comments

Tom Over a year ago

You are indeed very wrong. No need for keys, it's perfectly valid, see David's comment.

Quentin Over a year ago

There are no "lists". There are arrays and objects. While you can have an array of objects, nothing prevents you having an array of arrays.

trzewiczek Over a year ago

Thx! You posted your comment, while I was replaying - I saw it afterwards. Actually it's quite obvious - I don't know were my mind was.

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