Is it possible to destructure to already-declared variables?

Question

The following TypeScript works:

const carsAndTrucks = { cars: [], trucks: [] };
const { cars, trucks } = mapDealerInventory();

carsAndTrucks.cars = cars
carsAndTrucks.trucks = trucks

console.log(carsAndTrucks)

function mapDealerInventory() {
    return {cars: [1,2], trucks:['a', 'b']}
}

But is there a way to avoid having to set new variables just to destructure the return value of mapDealerInventory()? I was hoping this was possible:

{ carsAndTrucks.cars, carsAndTrucks.trucks } = mapDealerInventory() but it gives the error "Unexpected token ="

So if you declare an object with its property types first, what's the cleanest way to set those properties from a function that returns their values in an object (or an array)?

If `carsAndTrucks` only has `cars` and `trucks`, why destructure at all? Might be easier to just reassign — CertainPerformance, Jun 25 '18 at 10:25
Well, I simplified a bit. In this case, carsAndTrucks actually has more properties than just those two. — redOctober13, Jun 25 '18 at 11:21

score 2 · Answer 1 · answered Mar 12 '20 at 22:09

2

This should work:

({ cars, trucks } = carsAndTrucks)

PLs see this answer as well

How to destructure an object to an already defined variable?

answered Mar 12 '20 at 22:09

R Claven

1,160
2
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score 1 · Answer 2 · answered Jun 25 '18 at 11:47

Use Object.assign() to set multiple fields on an object:

const { cars, trucks } = mapDealerInventory();
Object.assign(carsAndTrucks, { cars, trucks });

Or, if you don't need cars and trucks variables for anything else and mapDealerInventory() returns only these two fields:

Object.assign(carsAndTrucks, mapDealerInventory());

carsAndTrucks will retain all other properties, and cars and trucks will be changed.

Is it possible to destructure to already-declared variables?

2 Answers2