TypeScript: extending imported enum

Question

I can merge enum declarations within a single file e.g.

export enum Test {
  value1 = \'value1\',
  value2 = \'value2\'
}

export enum          


        

Answer 1

I saw a way that you can add additional function/method in an existing enum. this is by create the function within a namespace similar to the enum type: Here

enum Weekday {
    Monday,
    Tuesday,
    Wednesday,
    Thursday,
    Friday,
    Saturday,
    Sunday
}
namespace Weekday {
    export function isBusinessDay(day: Weekday) {
        switch (day) {
            case Weekday.Saturday:
            case Weekday.Sunday:
                return false;
            default:
                return true;
        }
    }
}

const mon = Weekday.Monday;
const sun = Weekday.Sunday;
console.log(Weekday.isBusinessDay(mon)); // true
console.log(Weekday.isBusinessDay(sun)); // false

You can see the complete information here https://basarat.gitbooks.io/typescript/docs/enums.html at section "Enum with static functions"