How can a enum member be aliased in TypeScript?

Question

I have a below enum in TypeScript:

enum RoleTypes {
  None,
  Admin,
  SuperAdmin
}

When I run the following code:

var roleName = RoleTypes[RoleTypes.SuperAdmin];

the value of the variable roleName is SuperAdmin.

Is it possible to change it to a custom name 'Super Administrator', and how do I do this?

score 9 · Answer 1 · edited May 23 '17 at 12:34

9

As of TypeScript 2.4 you can assign string values directly to enum members

enum RoleTypes{
  None = "None",
  Admin = "Administrator",
  SuperAdmin = "Super Administrator"
}

Also see here

edited May 23 '17 at 12:34

Community

1
1

answered May 14 '17 at 08:00

Yaakov Ellis

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Not tried as it's not released. In typescript 2.4, what's the value of RoleTypes.None, 0 or 'None'? – L.W May 14 '17 at 08:20
I would like RoleTypes.None remains 0, and RoleTypes[RoleTypes.None] has value 'None'. or RoleTypes.SuperAdmin remains value 2 and RoleTypes[RoleTypes.SuperAdmin] has value 'Super Administrator'. Is it possible? – L.W May 14 '17 at 08:27
According to the commit in GH, you can have mixed types for enum, including int and string – Yaakov Ellis May 14 '17 at 08:31
what are you using this with? If you are using something like angular2 or vuejs you can use a pipe/filter as a temporary solution – Daniel Ormeño May 14 '17 at 08:47
1

@L.W You can always use `next` as TypeScript version (e.g. package.json) to try it out. Now `next` is already 2.5 – sebilasse Jun 14 '17 at 11:14

score 9 · Accepted Answer · edited Nov 03 '20 at 20:53

You can use a seperate object or array for this (Playground):

enum RoleTypes {
    None,
    Admin,
    SuperAdmin
}

let RoleTypesDisplay: { [index: number]: string } = {};
RoleTypesDisplay[RoleTypes.None] = "None";
RoleTypesDisplay[RoleTypes.Admin] = "Administrator";
RoleTypesDisplay[RoleTypes.SuperAdmin] = "Super Administrator";

var roleName = RoleTypesDisplay[RoleTypes.SuperAdmin];
alert(roleName);

// because RoleTypes is a number based enum that starts with 0 this is equals to 
RoleTypesDisplay = ["None", "Administrator", "Super Administrator"];

var roleName = RoleTypesDisplay[RoleTypes.SuperAdmin];
alert(roleName);

score 9 · Answer 3 · answered May 14 '17 at 11:46

9

Yes, simply create an alias using a quoted identifier

enum RoleTypes {
 None,
 Admin,
 SuperAdmin,
 'Super Administrator' = SuperAdmin 
}

answered May 14 '17 at 11:46

Aluan Haddad

29,886
8
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score 4 · Answer 4 · answered Nov 12 '21 at 01:25

Combining Markus's answer with Use Enum as restricted key type in Typescript, you can use eithers of the following syntaxes to constrain object keys

Either { [key in RoleTypes]: string } or Record<RoleTypes, string>

enum RoleTypes {
  None,
  Admin,
  SuperAdmin
}

let RoleTypesDisplay: Record<RoleTypes, string> = {
    [RoleTypes.None]: "None",
    [RoleTypes.Admin]: "Administrator",
    [RoleTypes.SuperAdmin]: "Super Admin",
};

var roleName = RoleTypesDisplay[RoleTypes.SuperAdmin];

console.log(roleName);

Demo in TS Playground

Is there an easy way to export the `RoleTypesDisplay` as a constant or static collection for re-use? — user1007074, Jul 14 '23 at 16:33

How can a enum member be aliased in TypeScript?

4 Answers4

Demo in TS Playground