jQuery Get data-attribute of all checkbox into a string

I have a list of checkboxes that looks like this:

<input type="checkbox" class="pcb" value="1" data-id="99">
<input type="checkbox" class="pcb" value="2" data-id="98">
<input type="checkbox" class="pcb" value="3" data-id="97">

And originally I only needed the value inside the value attribute of the checked checkbox. I use this javascript/jquery code to do that:

var receiptNos = $("#result input:checkbox:checked").map(function () {
   return $(this).val();
}).get();

Using this code gives me: receiptNos = '1,2,3' Now I need to have another string variable that will hold the content of data-id of all checked checkboxes: receiptNos2 = '99,98,97'

I tried using:

var receiptNos2 = $("#result input:checkbox:checked").attr('data-id').map(function () {
   return $(this).val();
}).get();

but it doesn't work. Any ideas?