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 a.user

And I would like to change only the a.user.groups value. If I do this:

const b = Object.assign({}, a, {
  user: {
    groups: {}
  }
});

b doesn't have any other Property except b.user.groups, all others are deleted. Is there any ES6 way to only change the nested property, without loosing all the other, with Object.assign?

Answer 1

After some trying I could find a solution that looks pretty nice like that:

const b = Object.assign({}, a, {
  user: {
    ...a.user,
    groups: 'some changed value'
  }
});

To make that answer more complete here a tiny note:

const b = Object.assign({}, a)

is essentially the same as:

const b = { ...a }

since it just copies all the properties of a (...a) to a new Object. So the above can written as:

 const b = {
   ...a,          //copy everything from a
   user: {        //override the user property
      ...a.user,  //same sane: copy the everything from a.user
      groups: 'some changes value'  //override a.user.group
   }
 }