Destructuring with default objects for nested object

Question

I have a requirement where I have to take a couple of values from a nested object which when not available, should be taken from a default object. For example consider the following object:

const objToDestructure={
   someVal:3,
   anotherVal:4,
   outerObj:{}
}

If I want to take two field field1 and field2 from outerObj then what I was able to do was

const { someVal,anotherVal,outerObj = {field1:22,field2:33}}=objToDestructure;
const {field1,field2}=outerObj;

Is there anyway this can be shortened even more? I tried to do the following:

const { someVal,anotherVal,outerObj:{field1,field2} = {field1:22,field2:33}}=objToDestructure;

But I got both the values as undefined. Is there any reason why this won't work but the individual assignment does?

just as a suggestion, shorter does not imply more readable. Sometimes destructuring nested objects can be a bit trickier to read for the rest of the devs — Gonzalo.-
– Gonzalo.-, Commented Dec 16, 2019 at 20:18

Ori Drori · Accepted Answer · 2019-12-16 21:05:43Z

1

Because outerObj exists (it's not undefined) in objToDestructure, setting a default for it won't help in this case. Since it's an object, you can destructure field1 and field2 individually, and set a default for each of them:

Set a default empty object, and add a default value for each field:

const { outerObj:{ field1 = 22, field2 = 33} = {}} = objToDestructure;

Example:

const objToDestructure={
   someVal:3,
   anotherVal:4,
   outerObj:{}
}

const { outerObj: { field1 = 22, field2 = 33} = {}} = objToDestructure

console.log(field1, field2)

edited Dec 16, 2019 at 21:05

answered Dec 16, 2019 at 19:51

Ori Drori

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4 Comments

Nn Karthik Over a year ago

I know that for separate values it can be done. is there anyway that this can done in a shortened way where we give the defaults as an object instead of specifying separately each field?

Nn Karthik Over a year ago

option 2 is not visible

Ori Drori Over a year ago

Updated the answer.

Nn Karthik Over a year ago

in my attempt to make the question smaller i left out some details. terribly sorry. can you take a look now please

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