Sorting

const items = [{
  id: 'foo',
  index: 0
}, {
  id: 'bar',
  index: 1
}, {
  id: 'lipsum',
  index: 2
}];

// DRAG SORTING OCCURS!

[{
  id: 'foo',
  index: 0
}, {
  id: 'bar',
  index: 2
}, {
  id: 'lipsum',
  index: 1
}];

// How to inform the server?

// Method 1
server.update(items);
// Here are the items with their new index, update them mindlessly
// Advantage: straight forward
// Disadvantage: different clients need to ensure they handle the same sorting rules

// Method 2
server.sort({
  id: 'bar',
  newIndex: 2
});
// Here is the item that moved and its new index, you do the rest
// Advantage: client-side code is not concerned with how items are sorted
// Disadvantage: complicated, server has to find related items and reindex them
// exactly as the user intended in the UI