Typescript array type extends a base array type-CodePudding

I am looking for a way to extend the type of an array, ie having at least the base array elements and possibly other elements.

use case: to communicate with translations APIs, I defined a base languages array:

const languages = ['FR', 'EN'] as const;
type BaseLanguages = typeof languages;

The objective is to define some derived types, arrays which contains at least 'FR' and 'EN' and possibly other string languages.

Thanks for your help

CodePudding user response：

Maybe the spread operator can you help you here.

const languages = ['FR', 'EN'] as const;
type BaseLanguages = [...typeof languages, ...string[]];