function returning difference of two objects
example:
const object1 = { a: 1, b: 2, c: 3, };
const object2 = { a: 1, c: 4, d: 5, };
const result = diffObjects(object1, object2); /* result = { added: { d: 5, }, saved: { a: 1, }, updated: { c: 4, }, deleted: { b: 2, }, }; */