Automatically generate type from Array-CodePudding

I have a hypothetical api that returns color values based on user selection.

Take an array with string values:

const Input1 = ['red', 'blue', 'purple'];
const Input2 = ['blue', 'white'];

And the api returns objects:

const Response1 = {
  red: "#ff0000",
  blue: "#0000ff",
  purple: "#aa22ff"
}

const Response2 = {
  blue: "#0000ff",
  white: "#ffffff"
}

I can manually create the types:

type TResponse1 = {
  red: string;
  blue: string;
  purple: string;
}

type TResponse2 = {
  blue: string;
  white: string;
}

But is it possible to derive the type? Something along the lines of this:

type TGenerated1 = {[any-value-from-Input1: string]: string};
type TGenerated2 = {[any-value-from-Input2: string]: string};

CodePudding user response：

You can convert your arrays into unions and then use those unions as keys in your types:

const Input1 = ['red', 'blue', 'purple'] as const;
const Input2 = ['blue', 'white'] as const;

const Response1: TGenerated1 = {
    red: "#ff0000",
    blue: "#0000ff",
    purple: "#aa22ff"
}

const Response2: TGenerated2 = {
   blue: "#0000ff",
   white: "#ffffff"
}

type TGenerated1 = { [K in typeof Input1[number]]: string }
type TGenerated2 = { [K in typeof Input2[number]]: string};

Playground

CodePudding user response：

A similar approach to the asnwer posted before me.
But I would take the step using the type from the Response1/Response2 objects inside the record itself like so:

const Input1 = ['red', 'blue', 'purple'] as const;
type Input1Tuple = typeof Input1

const Input2 = ['blue', 'white'] as const;
type Input2Tuple = typeof Input2


const Response1 = {
  red: "#ff0000",
  blue: "#0000ff",
  purple: "#aa22ff"
}

const Response2 = {
  blue: "#0000ff",
  white: "#ffffff"
}

type TGenerated1 = Record<Input1Tuple[number], typeof Response1[Input1Tuple[number]]>
type TGenerated2 = Record<Input2Tuple[number], typeof Response2[Input2Tuple[number]]>