Question

44

Object.assign—override nested property

rated 0 times [ 48] [ 4] / answers: 1 / hits: 80494 / 8 Years ago, wed, january 11, 2017, 12:00:00

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?

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braydon

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2 Years ago

answered 8 Years ago bryonk · Accepted Answer

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

   }

 }