proposal:symbol enum #18408

Activity

1. kgtkr (kgtkr)

   changed the title [-]【SUGGESTIONS】symbol enum[/-] [+]proposal:symbol enum[/+] on Sep 12, 2017
2. Mohamed Hegazy (mhegazy)

   added

   SuggestionAn idea for TypeScriptAn idea for TypeScript

   on Sep 12, 2017
3. mhegazy commented on Sep 12, 2017

   

   Mohamed Hegazy (mhegazy)

   on Sep 12, 2017

   Contributor

   More actions

   We first need a way to treat symbols as literals, just like string and numeric literals. this is covered in #15473

   👍React with 👍9Reacted by Daniel Rosenwasser, Sean M. Vieira, kgtkr, Aluan Haddad, Nisim Joseph, Patrick Lienau, Khải, resynth1943 and Wes Roberts
4. nisimjoseph commented on Dec 23, 2017

   

   Nisim Joseph (nisimjoseph)

   on Dec 23, 2017

   More actions

   I see #15473 merged, does it mean we can use Symbols in Enum somehow?
   I want to use Enum with the Types: string, number or Symbol.
5. Mohamed Hegazy (mhegazy)

   added

   Awaiting More FeedbackThis means we'd like to hear from more people who would be helped by this featureThis means we'd like to hear from more people who would be helped by this feature

   on Jan 13, 2018
6. fbartho commented on Jan 18, 2018

   

   Frederic Barthelemy (fbartho)

   on Jan 18, 2018

   Last edited by fbartho

   More actions

   Not to bikeshed, but wouldn't a more consistent syntax be:

   enum Example: Symbol {
     X,Y,Z
   }
   // or
   enum Example<Symbol> {
     X,Y,Z
   }

   Rather than introducing a new keyword of symbol these options either use inheritance style, or Generics, and would pave the way for arbitrary-valued enums?

   👍React with 👍16Reacted by kgtkr, Wenlu Wang, Daniel Weiner, Summer Knight, Constantine Theocharis, Aaron J. Lang, Marko Harjula, Larry1123, resynth1943, Viktor Lazarev and 6 more
7. DanielRamosAcosta commented on Jun 27, 2018

   

   Daniel Ramos (DanielRamosAcosta)

   on Jun 27, 2018

   Last edited by DanielRamosAcosta

   More actions

   This would be very useful with Redux actions...

   👍React with 👍9Reacted by kgtkr, Will, Constantine Theocharis, Marko Harjula, kaorun343, Will, Gabrielle Langer, Phoscur and Sam Holmes
8. Larry1123 commented on Sep 12, 2019

   

   Larry1123 (Larry1123)

   on Sep 12, 2019

   More actions

   Is there something that would help move this issue?
   If it would just be making a PR at this point I might be able to do it, may need to be guided in the right direction to start.

   👀React with 👀1Reacted by Phoscur
9. littleclown commented on Jun 2, 2020

   

   old days (littleclown)

   on Jun 2, 2020

   More actions

   I've found an alternative way to do it, and I hope it helps:

   /**
    * Action types for StoreState.todo
    */
   export namespace TodoActionTypes {
     // Adding todo item
     export const ADD_ITEM = Symbol('@todo/ADD_ITEM')
     export type ADD_ITEM = typeof ADD_ITEM
   
     // Removing todo item
     export const DEL_ITEM = Symbol('@todo/DEL_ITEM')
     export type DEL_ITEM = typeof DEL_ITEM
   
     // Performing undo on StoreState.todo
     export const UNDO = Symbol('@todo/UNDO')
     export type UNDO = typeof UNDO
   
     // Performing redo on StoreState.todo
     export const REDO = Symbol('@todo/REDO')
     export type REDO = typeof REDO
   }
   
   
   /**
    * Action types for StoreState.todo
    */
   export type TodoActionTypes =
     | TodoActionTypes.ADD_ITEM
     | TodoActionTypes.DEL_ITEM
     | TodoActionTypes.UNDO
     | TodoActionTypes.REDO
10. cosmoarunn commented on Oct 3, 2020

    

    cosmoarunn

    on Oct 3, 2020

    Last edited by cosmoarunn

    More actions

    I've found an alternative way to do it, and I hope it helps:

    /**
     * Action types for StoreState.todo
     */
    export namespace TodoActionTypes {
      // Adding todo item
      export const ADD_ITEM = Symbol('@todo/ADD_ITEM')
      export type ADD_ITEM = typeof ADD_ITEM
    
      // Removing todo item
      export const DEL_ITEM = Symbol('@todo/DEL_ITEM')
      export type DEL_ITEM = typeof DEL_ITEM
    
      // Performing undo on StoreState.todo
      export const UNDO = Symbol('@todo/UNDO')
      export type UNDO = typeof UNDO
    
      // Performing redo on StoreState.todo
      export const REDO = Symbol('@todo/REDO')
      export type REDO = typeof REDO
    }
    
    
    /**
     * Action types for StoreState.todo
     */
    export type TodoActionTypes =
      | TodoActionTypes.ADD_ITEM
      | TodoActionTypes.DEL_ITEM
      | TodoActionTypes.UNDO
      | TodoActionTypes.REDO

    i guess this will do?

    export type TodoActionTypes =
      | ADD_ITEM
      | DEL_ITEM
      | UNDO
      | REDO
    
11. polomsky commented on Oct 20, 2020

    

    Tomáš Polomský (polomsky)

    on Oct 20, 2020

    More actions

    I have found another solution at https://fettblog.eu/symbols-in-javascript-and-typescript/ and I slightly improved it. Sadly, there is lot of code around it, but it gives pretty protection (compile time and runtime)

    const COLOR_RED = Symbol('COLOR_RED');
    const COLOR_ORANGE = Symbol('COLOR_ORANGE');
    
    // intentionally not part of the enum for demonstration
    const COLOR_GREEN = Symbol('COLOR_GREEN');
    
    // freeze needed for runtime protection
    export const colors = Object.freeze({
        COLOR_RED,
        COLOR_ORANGE,
    } as const);
    
    type ValuesWithKeys<T, K extends keyof T> = T[K];
    type Values<T> = ValuesWithKeys<T, keyof T>
    
    export type COLOR = Values<typeof colors>;
    
    function foo(val: COLOR) {
    
    }
    
    foo(COLOR_RED);
    foo(colors.COLOR_ORANGE);
    foo(COLOR_GREEN); // refused by typescript

    👍React with 👍1Reacted by Somnium7
12. alaboudi commented on Apr 10, 2023

    

    Yazan Alaboudi (alaboudi)

    on Apr 10, 2023

    More actions

    To continue on the same vein as this thread, I think enum values should be symbolic by default rather than integers. That's the whole point of enums to begin with. It would be best if developers don't even know the underlying value but rather treat enums as a union of interrelated Symbols. It would promote developers to have much better coding standards.

    So something like

    enum TrafficColors = {
     Red,
     Yellow,
     Green
    }

    would be best if translated into something like

    var TrafficColors = {
     Red: Symbol('Red'),
     Yellow: Symbol('Yellow'),
     Green: Symbol('Green')
    }

    with keys used as the arguments in Symbol constructors to have google error reporting at runtime.

    👍React with 👍2Reacted by Michael Vlasov and Somnium7
13. Somnium7 commented on Aug 27, 2026

    

    Somnium7 (Somnium7)

    on Aug 27, 2026

    More actions

    I have rediscovered same ideas guys people mentioned above and made small library just for this. No key name repetition needed as in Tomas' example, but still verbose.

    import { SymbolEnum } from 'ts-symbol-enum';
    
    const Status = SymbolEnum(
      'Status',
      [class { static readonly PENDING: unique symbol; }, 'pending'],
      [class { static readonly APPROVED: unique symbol; }, 'approved'],
      [class { static readonly REJECTED: unique symbol; }, 'rejected'],
    );
    type Status<K = unknown> = SymbolEnum<typeof Status, K>;
    
    const anyStatus: Status = Status.PENDING;

    Take a look if you're interested: ts-symbol-enum (npm)