Safely turning a JSON string into an object

Given a string of JSON data, how can you safely turn that string into a JavaScript object?

Obviously you can do this unsafely with something like...

var obj = eval("(" + json + ')');

...but that leaves us vulnerable to the json string containing other code, which it seems very dangerous to simply eval.

From stackoverflow Matt Sheppard

• I'm not sure about other ways to do it but here's how you do it in Prototype (JSON tutorial).

  new Ajax.Request('/some_url', {
    method:'get',
    requestHeaders: {Accept: 'application/json'},
    onSuccess: function(transport){
      var json = transport.responseText.evalJSON(true);
    }
  });
  

  Calling evalJSON() with true as the argument sanitizes the incoming string.

  From Mark Biek

• JSON.org has JSON parsers for many languages including 4 different ones for Javascript. I believe most people would consider json2.js their goto implementation.

  From John

• JS Guru Douglas Crockford has written a parseJSON function which you download here

  AllenJB : The code pointed to by this link has been superceded by json2.js mentioned above.
  From Manu

• If you're using jQuery, you can also just do $.getJSON(url, function(data) { });

  Then you can do things like data.key1.something, data.key1.something_else, etc.

  Alexandre C. : you are using jQuery, aren't you ?
  From Leanan

• $.ajax({ url: url, dataType: 'json', data: data, success: callback });

  ---

  The callback is passed the returned data, which will be a JavaScript object or array as defined by the JSON structure and parsed using the $.parseJSON() method.

  From Prahlad

• Don't bother with that crap. If you're using jQuery just use:

  jQuery.parseJSON( jsonString );

  It's exactly what you're looking for

  http://api.jquery.com/jQuery.parseJSON/

  From Alex V