Uniqueness in arrays with simple datatype

[SpinGit]

Thank you very much for the nestedObjectAssign function. It helps me to update data into aws dynamodb.

describe("array object", () => {

it("should add text to empty comments array", () => {
  const dbData = {comments: []}
  const requestData = {comments: ["foo"]}

  nestedObjectAssign(dbData, requestData);
  expect(dbData).toStrictEqual({comments: ["foo"]});
});

it("should NOT add text duplicates", () => {
  const dbData = {comments: ["foo"]}
  const requestData = {comments: ["foo"]}

  nestedObjectAssign(dbData, requestData);
  expect(dbData).toStrictEqual({comments: ["foo"]});
});

it("should NOT change existing properties in db, if they not updated via request", () => {
  const dbData = {comments: ["bar", "foo"]}
  const requestData = {comments: ["foo"]}

  nestedObjectAssign(dbData, requestData);
  expect(dbData).toStrictEqual({comments: ["bar", "foo"]});
});

});

To realize green tests i changed the function to typescript and
changed line 23 to target[key] = [...new Set([...target[key], ...source[key]])]

Hopefully it helps someone.