Refer: Easy - Tuple to Object

Describe

Give an array, transform into an object type and the key/value must in the given array.

For example

code snippetCopytypescript
const tuple = ['tesla', 'model 3', 'model X', 'model Y'] as const

// expected { tesla: 'tesla', 'model 3': 'model 3', 'model X': 'model X', 'model Y': 'model Y'}
type result = TupleToObject<typeof tuple>

Test Cases

code snippetCopytypescript
import { Equal, Expect } from '@type-challenges/utils'

const tuple = ['tesla', 'model 3', 'model X', 'model Y'] as const

type cases = [
  Expect<
    Equal<
      TupleToObject<typeof tuple>,
      { tesla: 'tesla'; 'model 3': 'model 3'; 'model X': 'model X'; 'model Y': 'model Y' }
    >
  >,
]

// @ts-expect-error
type error = TupleToObject<[[1, 2], {}]>

Solution

When the type of T is Object, We can use keyof to get all keys in T. However, if the T's type is array, we can use the type number to get all values.

code snippetCopytypescript
type TupleToObject<T extends readonly any[]> = {
  [P in T[number]]: P
}