CartThrob forms JSON response

gistfile1.js

//successful form submission
{
  "success": 1,
  "errors": {},
  "return": "http://yoursite.com/path/to",
  "XID": "0394wjg0w9rj0e65gmaode509gj095e", //only if secure forms is turned on
  "cart_total": 100,
  "cart_subtotal": 80,
  "cart_discount": 0,
  "cart_tax": 10,
  "cart_shipping": 10
}

//failed form submission
{
  "success": 0,
  "errors": {
    0: "This item is out of stock",
    "title": "You must submit a title"
  },
  "return": "http://yoursite.com/path/to",
  "XID": "0394wjg0w9rj0e65gmaode509gj095e" //only if secure forms is turned on
}

Returning total_items_count would be really useful here