Destructuring - Assign selected props to a new variable

💡 Ideas
1

I often run into this scenario where in need of a portion of an object. destructuring surely helps in grabbing what is needed. the annoyance occur when the portion is used as a new object - forcing the code to like this:

const  {b, d} = {a: 10, b: 20, c: 30, d: 40}
someFunction({b,d});

this is a duplication of the properties and is a pitfall in some cases where you might leave out few properties unwillingly (when it comes to large portions from large objects).

a syntax such as the following might achieve better stability, assurance and nonrepetitive code.

const  {b, d} as newObj = {a: 10, b: 20, c: 30, d: 40}

it's currently possible to gather the rest of unmentioned properties with {...rest} but I think in most cases it is way more essential to select and group the destructured properties.

5 Likes
2

Are you familiar with the "as patterns" proposal?

IIRC, that's part of zkat's larger pattern matching proposal.

2 Likes
3

Seems just right. but this proposal is 2 years old and there's no evidence of progress :confused:
it is also really similiar and covers more patterns.

I'd vote for it!

1 Like
4

Unfortunately, zkat is not able to help with TC39 anymore through no fault of her own.

If someone did want to pick that up though, they could build on her work.

1 Like
5

zkat's current employer is an ecma member, so there's no barrier to their participation.

2 Likes
6

Hi, I've came across this issue and I'm also interested in it. Is there any way I can start help contribute to this proposal? Maybe I can help draft the stage-0 version of the as-proposal which is based on zkat's version.

Thanks!

1 Like
7

I think the property shorthand improvements proposal would have a much better chance at adoption, and is much more useful.

The syntax to achieve the goal from the OP's example:

const obj = {a: 10, b: 20, c: 30, d: 40}
someFunction({obj.b, obj.d});
8

wanna collaborate on this?

1 Like
9

|FRIEND I love your proposal is exactly what I have always needed.

const {b=1, d, e = 50} as newObj = {a: 10, b: 20, c: 30, d: 40}

i like this

console.log(newObject) // { b:20, d:40, e:50 }

10

I like this. Wish there was an easier way to do that.