TL;DR

const STATUS = constList('AVAILABLE', 'BOUGHT', 'REJECTED')
type Status = keyof typeof STATUS;

// type Status = 'AVAILABLE' | 'BOUGHT' | 'REJECTED';

The Problem

It’s always better to work with constants instead of having strings all over your code. In TS we can implement a list of constants with enums like this:

// 👍 Good
enum STATUS {
  AVAILABLE = 'AVAILABLE',
  BOUGHT = 'BOUGHT',
  REJECTED = 'REJECTED',
}

type Status = keyof typeof STATUS;

With this simple solution, we have the list and the corresponding type, great!

The Solution

The main issue is enums is that we need to repeat the name of the value as a string. To solve this we can implement a helper function like the following:

function constList<T extends string>(
  ...args: Array<T>
): {
  [K in T]: K;
} {
  return args.reduce((accumulator, value) => {
    accumulator[value] = value;
    return accumulator;
  }, Object.create(Object.prototype));
}

This function converts the list of parameters in an object with shape:

{
  AVAILABLE: 'AVAILABLE',
  BOUGHT: 'BOUGHT',
  REJECTED: 'REJECTED'
}

Then, we can use the function like this:

// 👍👍 Better!
const STATUS = constList('AVAILABLE', 'BOUGHT', 'REJECTED')

type Status = keyof typeof STATUS;

This way is simpler 😎.

Types of string arrays

Also you can get types of an array in this way

const animals = ['cat', 'dog', 'mouse'] as const
type Animal = typeof animals[number]

// type Animal = 'cat' | 'dog' | 'mouse'