Using enum as interface key in typescript

Question

I was wonder if I can use enum as an object key in interfaces.. I've built a little test for it:

export enum colorsEnum{ red,blue,green }  export interface colorsInterface{ [colorsEnum.red]:boolean, [colorsEnum.blue]:boolean, [colorsEnum.green]:boolean } 

When I run it I'm getting the following error:

A computed property name in an interface must directly refer to a built-in symbol. 

I'm doing it wrong or it just not possible?

Answer 1

You can try with type:

export enum colorsEnum{     red, blue, green }  export type colorsInterface = {     [key in colorsEnum]: boolean; };  let example: colorsInterface = {     [colorsEnum.red]: true,     [colorsEnum.blue]: false,     [colorsEnum.green]: true }; 

Or if you do not want to use all keys: add a ?

export type colorsInterface = {     [key in colorsEnum]?: boolean; };  let example: colorsInterface = {     [colorsEnum.red]: true,     [colorsEnum.blue]: false }; 

Answer 2

OK, the key idea is to convert the Enum to the correct Type and to extends the Interface with it: You can check it out in live code here.

const enum Enum {     key1 = "value1",     key2 = "value2",     key3 = "value3", } type EnumKeys = keyof typeof Enum; type EnumKeyFields = {[key in EnumKeys]:boolean}  interface IEnumExtended extends EnumKeyFields {     KeyEx1:boolean;     KeyEx2:string; }  // Test it const enumInstance: IEnumExtended = {  }; 

when you inside the enumInstance you will get autocomplete for the Enum keys and not the values.