Declare union type from a values of array [duplicate]

Question

export const files = ['a', 'b', 'c']

export type File = 'a' | 'b' | 'c'

How do I declare this File type without repeating the values like 'a', 'b', 'c'.

An uncanny duplicate: Derive union type from tuple/array values — k.tten
– k.tten, Commented Oct 7, 2022 at 14:18

mickl · Accepted Answer · 2022-10-07 14:16:58Z

1

You can use the typeof with number as index syntax. Note that as const is needed in your array definition:

export const files = ['a', 'b', 'c'] as const;
export type File = typeof files[number];

answered Oct 7, 2022 at 14:16

mickl

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