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javascriptarraystypescripttypes
Michael
Michael

Reputation: 7113

Typescript: How can I define a type from an string array?

Currently I do:

export const CValidEbookTypes = ['epub', 'mobi', 'pdf', 'azw3', 'txt', 'rtf'];
export type IEbookType = 'epub' | 'mobi' | 'pdf' | 'azw3' | 'txt' | 'rtf';

to have an array of valid book types and a typescript type, that defines them. This look quite redundant.

Is there a way to define the type using the array? My goal is obviously to avoid writing the book type twice. So any other solution would also be welcome.

Upvotes: 1

Views: 66

Answers (1)

Johannes Reuter
Johannes Reuter

Reputation: 3547

By using as const, typescript infers the string literals as type for CValidEbookTypes. Then you can use typeof CValidEbookTypes[number]:

export const CValidEbookTypes = ['epub', 'mobi', 'pdf', 'azw3', 'txt', 'rtf'] as const;
export type IEbookType = typeof CValidEbookTypes[number];
// IEbookType will be "epub" | "mobi" | "pdf" | "azw3" | "txt" | "rtf"

Upvotes: 2

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