.sortable('toArray', {attribute: 'data-id')) returns a list of jQuery objects

[bturner1273]

Fiddle:
https://jsfiddle.net/bturner1273/frgnw4cj

In my code I end up have to do:
console.log(group.sortable('serialize').get(0).filter(i => i['id'] !== undefined).map(i => i.id));

instead of:
console.log(group.sortable('toArray', {attribute: 'data-id'}));

output of group.sortable('toArray', {attribute: 'data-id'}):

expected result is an array of strings or numbers i.e.
[0,1,2,3,4] or ['0', '1', '2', '3', '4']