Object.assign—override nested property

Question

I have an Object a like that:

const a = {
  user: {
   …
   groups: […]
   …
  }
}

whereby there are a lot more properties in

Answer 1

Small fine tune of phillips first answer.

const object1 = {
  abc: {
    a: 1
  }
};

const object2 = {
  abc: {
    b: 2
  }
};

Object.assign(object1, {
    abc: {
        ...object1.abc,
        ...object2.abc
    }
});

console.log(object1);
// Object { abc: Object { a: 1, b: 2 } }