Is it somehow possible to compare an array of objects based on a key?

[mmailaender]

e.g.:

const array1 = [
  {
    id: '1',
    originalProperty: true
  },
  {
    id: '2',
    originalProperty: true
  }
  ];
  
  const array2 = [
  {
    id: '1',
    originalProperty: true,
    newProperty: true
  },
  {
    id: '3',
    originalProperty: true
  }
];

diff(database, current, { key: "id" });
// [
//	{type: "UPDATE", key: ["id"], value: "1"},
//	{type: "DELETE", key: ["id"], value: "2"},
//	{type: "CREATE", key: ["id"], value: "3"},
// ]

[AsyncBanana]

The best way to do this would be to convert it into an object and then diff it. e.g.

const array1 = [
	{
		id: '1',
		originalProperty: true
	},
	{
		id: '2',
		originalProperty: true
	}
];

const array2 = [
	{
		id: '1',
		originalProperty: true,
		newProperty: true
	},
	{
		id: '3',
		originalProperty: true
	}
];
function convert(array) {
	const res = {};
	for (let arrayEl of array) {
		res[arrayEl.id] = arrayEl;
	}
	return res;
}
diff(convert(array1), convert(array2))
/*
[
  { type: "CREATE", path: [ "1", "newProperty" ], value: true },
  {
    type: "REMOVE",
    path: [ "2" ],
    oldValue: { id: "2", originalProperty: true }
  },
  {
    type: "CREATE",
    path: [ "3" ],
    value: { id: "3", originalProperty: true }
  }
]
*/

Does that work for your use case? I might have misinterpreted your question.