How to grab JavaScript destructured parameters independent of variable name?

Question

Wish to enact upon arguments but with defaults defined

In my quest for self-documenting code with destructuring but being DRY wanting to do this...

async function shampoo({ lather = true, rinse = true, repeat = 2 } = {}) {
  await api.dogWasherMachine(magicalArguments) // ???
  // don't want to have to do this:
  // api.dogWasherMachine({ lather, rinse, repeat })
  // currenty arguments is {} and actual input is defined
}

How do I get these magical arguments that are defined?

arguments do not have the default input defined but how can I do this?

It's really not at all clear what you're talking about here. — Pointy, Jun 27 '19 at 00:30
You cannot, you must manually assemble a new object with only those properties. — zerkms, Jun 27 '19 at 00:31
Do you want to do `await api.dogWasherMachine(arguments[0])`? — nem035, Jun 27 '19 at 00:32
you could move the destructuring into the `dogWasherMachine` function ( so your function definitions would look like :`function dogWasherMachine({ lather: true, rinse: true, repeat: 2 })` and `function shampoo(params={})` and then call `dogWasherMachine(params)` — 88jayto, Jun 27 '19 at 00:35
If I ever become a recruiter, at least I know how to make honey. — King Friday, Jun 27 '19 at 00:38
Your destructuring assignment is actually invalid. It should be `async function shampoo({ lather = true, rinse = true, repeat = 2 } = {})` — BlueWater86, Jun 27 '19 at 00:59

score 1 · Accepted Answer · answered Jun 27 '19 at 00:32

1

It's not possible to do it in the parameters alone - destructuring necessarily extracts each property into an independent named variable, without leaving a reference to the original object behind. You'll have to do it with another statement, eg:

async function shampoo(param = {}) {
  const defaultObj = {
    lather: true,
    rinse: true,
    repeat: 2
  };
  await api.dogWasherMachine({ ...defaultObj, ...param });
}

answered Jun 27 '19 at 00:32

CertainPerformance

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I like this answer as it accomplishes what I want to do. – King Friday Jun 27 '19 at 00:34

score 1 · Answer 2 · answered Jun 27 '19 at 01:10

1

I use destructuring assignment to to self document inheritable classes that are used as interfaces. On construction I get all of the benefits of intellisense and when calling an API everything stays nice and DRY.

class washable {
  constructor({ lather = true, rinse = true, repeat = 2 } = {}) {
    this.lather = lather
    this.rinse = rinse
    this.repeat = repeat
  }
}

class dog extends washable {
  async shampoo() {
     await api.dogWasherMachine(this)
  }
}

answered Jun 27 '19 at 01:10

BlueWater86

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but... count the number of times you wrote "repeat". – King Friday Jun 27 '19 at 01:11
Agreed but without destructing assignment in your function call (like in your question) how is the function self documenting to external code? – BlueWater86 Jun 27 '19 at 01:16
Yah you are right and thanks for the answer. I would probably use TypeScript in that case. – King Friday Jun 27 '19 at 01:21
I assume by TypeScript you mean JSDoc definitions? Personally I would like to see the ability to destructure directly onto an instance through a class method similar to the answer [here](https://stackoverflow.com/a/40624564/3236706) – BlueWater86 Jun 27 '19 at 01:30

How to grab JavaScript destructured parameters independent of variable name?

Wish to enact upon arguments but with defaults defined

2 Answers2