Generic to transform array of string variables to union type-CodePudding

const A= "Hello"
const B= "Bye"
const C="Foo"

const myArrayOfConstants=[A,B,C]

type ConvertArrayToUnion<myArrayOfConstants> ==> Expected type output: "Hello" | "Bye" | "Foo".

I tried with

type ConvertArrayToUnion<T extends readonly string[]>= T[number]

But in this case I am not passing an array of strings, but the variable name of each constant (which I guess it is a tupple?) so it doesn't work.

CodePudding user response：

Try like this:

const A= "Hello"
const B= "Bye"
const C="Foo"

const myArrayOfConstants=[A,B,C] as const;

type test = typeof myArrayOfConstants[number]

CodePudding user response：

You could use as const and typeof

const A= "Hello";
const B= "Bye";
const C= "Foo";

const myArrayOfConstants = [A, B, C] as const;
type MyType = typeof myArrayOfConstants[number]; // "Hello" | "Bye" | "Foo"

CodePudding user response：

const convert = myArrayOfConstants as const;

// type UnionType = "Hello" | "Bye" | "Foo"
type UnionType = typeof convert[number];

hope it can help