How to get an array of objects with key to show diff?

[rmtuckerphx]

I have the following code:

var diffJson = require("diff-json")

oldArray = [
  {
    "id": "a",
    "count": 1
  },
  {
    "id": "b",
    "count": 0
  }
];

newArray = [
  {
    "id": "b",
    "count": 1
  },
  {
    "id": "a",
    "count": 3
  }
];

var diffs = diffJson.diff(oldArray, newArray);

And the result is showing as:

[Object {changes: [, ], embededKey: "$index", key: "$root", type: "update"}]

What should the call to .diff be?
What do the other params (path, embededObjKeys, keyPath) mean?

[lveillard]

If you want that one to work, you will need to sort the arrays, for example like this:
sort((x, y) => (x.id > y.id ? 1 : -1)

[marke-apexit]

I would also like to compare two arrays by a key (or multi-part key) that I define. I see the suggestion for sorting the arrays, but I don't think that will deal with misalignment due to 'gaps' in the arrays without defining a key.