Jquery, AJAX and JSON

Jquery, AJAX and JSON

Hello All,

I have been able to execute AJAX and JSON successfully in the past however I am struggling with the following JSON and not sure what I am doing wrong.  For the given JSON
 
{
  "invoices": {
    "INV123589": {
      "custname": "Customer A",
      "total": "$100"
    },
    "INV123554": {
      "custname": "Customer B",
      "total": "$200"
    }
  }
}










 
I am trying to parse it via an ajax call:
 
$.ajax({
      url: 'someurl',
      type: 'GET',
      dataType: 'json',
      success: function(data){
            alert(data.length);
            alert(data.invoices.length);
            alert(data[0].length);
      });

The ajax executes however all the alert messages are coming up as null.  I am interested in retreiving the invoice number, example INV123589, and its customername and total.  Any help in this matter will be greatly appreciated