Make the returned JSON into a global array.

I am using the following to bring back some JSON data.

I want to use

var selectedArray =[] // global array.

How do I assign the returned data to selectedArray

       ajax :       {
                            'url' :  'http://www.xxxx.com/php/xxxx.php',
                            "type": "POST",
                                  "data": {
                                                'selectedInvoiceID': selectedInvoiceID
                                              }

                          },

Cheers

Steve Warby