CODEWITHSUNDEEP
typescript
Timothy
Timothy

Reputation: 3593

How to convert Enum in TypeScript to array which returns keyof typeof Enum?

Following enum

export enum Types {
    Type1 = 1,
    Type2 = 2,
    ...
}

is converted into array with following function

export function EnumKeys<T>(obj: object): string[] {
    return Object.keys(obj)
        .filter(value => isNaN(Number(value)) === false)
        .map(key => obj[key]);
}

EnumKeys returns string[], but I need it to return [keyof typeof T]

Upvotes: 2

Views: 448

Answers (1)

Titian Cernicova-Dragomir
Titian Cernicova-Dragomir

Reputation: 249606

Object.keys returns string[] by design (see canonical question here). You will need to use a type to transform Object.keys(obj) into Array<keyof T> (I assume for the type of obj you wanted to use the T type parameter).

 enum Types {
    Type1 = 1,
    Type2 = 2,

}

function EnumKeys<T>(obj: T) {
    return (Object.keys(obj) as Array<keyof T>)
        .filter(value => isNaN(Number(value)) !== false); // just directly take the non number keys.
}

let o = EnumKeys(Types) 
console.log(o)

play

Upvotes: 3

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