missing ] after element list parsing JSON

I was working on a little web application front end submitting a form and processing a result asynchronously using jQuery. I wrote a little JavaScript snippet that looks something like the following:

$.post( "submitForm.jsp", theForm.serialize(), function(data) {
  var res = eval('(' + data + ')');
  // do something with the result
});

Yeah, I know, eval() probably isn’t the best choice here but we need to support IE7 which doesn’t support JSON.parse natively. Anyway, after submitting I get the following error:

error: missing ] after element list parsing JSON

Turns out that jQuery will try to figure out if the result is JSON and parse it automatically. In this case data is already a JavaScript object and not a JSON string waiting to be parsed.