Typescript - Convert from Array of types to Object of types-CodePudding

I need this type

type Sample = [a: string, b: number]

to be converted to

type Sample2 = { a:string, b:number}

I need this to pass arguments of a function in a paramenter, in form of an object

function example(otherFunctionParameters: Parameters<typeof otherFunction>){}

I don't want to pass an array in the parameter.

How can I achieve this ?

CodePudding user response：

It has to be passed in as an array unfortunately because an object is a different type than an array.

type Sample = [a: string, b: number]
type Sample2 = { a:string, b:number}

function example(otherFunctionParameters: Sample){}
function example2(otherFunctionParameters: Sample2){}

example(['b', 3])
example2({a: 'b', b: 2})

I recommend changing the signature type of the calling function. If this is not possible, an array should work just fine.

CodePudding user response：

Because you can't manipulate tuple labels in the type system, the best you can do is manually supply a tuple of property keys, one for every parameter in the original function.

By adapting some utilities from this answer by jcalz, here's a generic utility that will give you a mapped object for the parameters in a function: You supply the function type and a tuple of labels for each parameter:

TS Playground

type ZipTuples<Keys extends readonly any[], Values extends readonly any[]> = {
  [K in keyof Keys]: [Keys[K], K extends keyof Values ? Values[K] : never];
};

type ZipTuplesAsObject<
  Keys extends readonly PropertyKey[],
  Values extends readonly any[],
> = { [T in ZipTuples<Keys, Values>[number] as T[0]]: T[1] };

type ParamsAsObject<
  Fn extends (...params: readonly any[]) => any,
  Keys extends readonly PropertyKey[],
> = ZipTuplesAsObject<Keys, Parameters<Fn>>;


// Use

declare function otherFunction (
  irrelevantLabel: string,
  alsoNotUsed: number,
  onlyTheTypesMatter: boolean,
): void;

function example (objectParam: ParamsAsObject<typeof otherFunction, ['a', 'b', 'c']>) {
  // objectParam; // { a: string; b: number; c: boolean; }
  const {a, b, c} = objectParam;
  a; // string
  b; // number
  c; // boolean
}