How do I typecheck, objects in a parameter, in a typescript function

Question

I am having issues typechecking some parameters in a function

function myfun({carengine,cartransmission})
{

   // Some code here

}

I wish to type check it so it is like this function myfun({carengine:CarEngine,cartransmission:CarTransmission})

However this does not work.

How do I typecheck these parameters?

Does this answer your question: https://stackoverflow.com/questions/8407622/set-type-for-function-parameters — Steve, Sep 14 '21 at 01:18

Phil · Answer 1 · 2021-09-14T01:34:01.887

1

Define the type for the structured function argument, eg

interface Car {
  carengine: CarEngine,
  cartransmission: CarTransmission
}

function myfun({ carengine, cartransmission }: Car)
{
   // Some code here
}

Typescript Playground

If you already have a Car type and only want to specify certain properties for your myfun function, you can use Pick

interface Car {
  carengine: CarEngine,
  cartransmission: CarTransmission,
  doors: number
}

function myfun({ carengine, cartransmission }: Pick<Car, "carengine" | "cartransmission">)
{
   // Some code here
}

You can also define the argument type inline but it can get messy fast

function myfun({ carengine, cartransmission }: { carengine: CarEngine, cartransmission: CarTransmission })
{
   // Some code here
}

edited Sep 14 '21 at 01:34

answered Sep 14 '21 at 01:21

Phil

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@TypeScriptProgrammer1234 If this worked, don't forget to mark it as the accepted answer. – samthecodingman Sep 14 '21 at 02:40
@TypeScriptProgrammer1234 please also dont forget to upvote it :) – captain-yossarian from Ukraine Sep 14 '21 at 06:01

How do I typecheck, objects in a parameter, in a typescript function

1 Answers1