JS. Object destructuring with default value not working

Question

Object:

    fruits {
      citrus {
        lime {
          id
        }
      }
      berries {
        ...
      }
    }

Destructuring fruits to reach lime:

const { citrus: { lime } = {} } = fruits;

My understanding is that if citrus is null, the destructuring will work and the value of lime will be an empty object {}. However this is not working. Am I missing something?

Default only works for `undefined` not null values: [destructuring assignment default value](https://stackoverflow.com/questions/49233891) (I've already closed with another reason. You can close it as a duplicate of this) — adiga, Jun 24 '20 at 17:38
I guess @adiga is correct. Surprising it works for '', undefined (returns undefined) but not for `null` — ABGR, Jun 24 '20 at 17:43
Okay, well, that solves my issue I guess. Thanks for answering. — wazus, Jun 24 '20 at 17:46
@ABGR default won't work for empty string either. It's just that it will try to access `lime` property from an empty string: `"".lime` and it's not an error, it will return `undefined` — adiga, Jun 24 '20 at 17:47

score -1 · Answer 1 · answered Jun 24 '20 at 17:41

-1

You should do like this:

const { citrus = {} } = fruits;

or

const { citrus: { lime = {} } } = fruits;

but not how you showed it, it doesn't work like this

answered Jun 24 '20 at 17:41

Evgeny Klimenchenko

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If `citrus` is null, this won't work either – adiga Jun 24 '20 at 17:42
I am pretty sure it won't work like this `const { citrus: { lime } = {} } = fruits;` what variable will be assign to empty object? – Evgeny Klimenchenko Jun 24 '20 at 17:44
The second block in your asnwer is not assigning default value when `citrus` is `undefined`. – adiga Jun 24 '20 at 17:45
The second part is just for example, to show in perspecitve – Evgeny Klimenchenko Jun 24 '20 at 17:46
*"I'm pretty sure it doesn't work like this: `const { citrus: { lime } = {} } = fruits;`*" It does. You can easily test it. It will assign empty object literal when `citrus` is undefined. – adiga Jun 24 '20 at 17:51
I did before answering doesn’t work for me, it is pointless default – Evgeny Klimenchenko Jun 24 '20 at 17:52
It is not pointless. `const { citrus: { lime } = {} } = {}` will not throw an error. But `const { citrus: { lime={} } } = {}` will – adiga Jun 24 '20 at 17:54

JS. Object destructuring with default value not working

1 Answers1