Question

I have created a JSON object in php using json_encode and am attempting to display certain values of that object in javascipt through AJAX. I have no issue receiving the response from php but am getting ‘undefined’ when I try to access any value of the response using JSON notation.

Code snippet:

if (xmlhttp.readyState==4 && xmlhttp.status==200)
{
   var response = xmlhttp.responseText;
   alert(response);
   alert(response.data);
}

Output:

{"data":[{"cheese":"pork"},{"cheese":"chicken"}]} // Yes, I'm hungry right now.
undefined

EDIT: Thanks everybody for the responses. Wish I could give you all a check mark but I have selected the most helpful response.

Answer 1

You have to parse the json. This can be done through a simple call to eval, but this can only be done if you absolutely trust the returning server as he can make your script execute everything.

 var data = eval('('+response+')');

The way I would recommand if to use json2.js, a small javascript library that ius faster and will handle the parsing for you.

var data = JSON.parse(response);

It can be acquire from https://github.com/douglascrockford/JSON-js