TypeScript array to string literal type

Question

I currently have both an array of strings and a string literal union type containing the same strings:

const furniture = [\'chair\', \'table\', \'lamp\'];
ty         


        

Answer 1

The only adjustement I would suggest is to make the const guaranteed compatible with the type, like this:

type Furniture = 'chair' | 'table' | 'lamp';

const furniture: Furniture[] = ['chair', 'table', 'lamp'];

This will give you a warning should you make a spelling error in the array, or add an unknown item:

// Warning: Type 'unknown' is not assignable to furniture
const furniture: Furniture[] = ['chair', 'table', 'lamp', 'unknown'];

The only case this wouldn't help you with is where the array didn't contain one of the values.