Object.defineProperty doesn't define properties on 'this' #28694

Activity

1. Wesley Wigham (weswigham)

   added

   Domain: JavaScriptThe issue relates to JavaScript specificallyThe issue relates to JavaScript specifically

   Experience EnhancementNoncontroversial enhancementsNoncontroversial enhancements

   on Nov 27, 2018
2. Daniel Rosenwasser (DanielRosenwasser)

   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 Nov 28, 2018
3. Ryan Cavanaugh (RyanCavanaugh)

   added

   SuggestionAn idea for TypeScriptAn idea for TypeScript

   on Mar 7, 2019
4. xprommer commented on Jun 11, 2019

   

   Roman Bielte (xprommer)

   on Jun 11, 2019

   More actions

   Unfortunately it doesn't work in TS as well,
   if you run this in TS playground (I guess it has the latest TS version)

   let obj = {};
   Object.defineProperty(obj, "x", { value: "hello", writable: false });
   
   obj.x.toLowercase();

   then it will show only one error message:
   "Property 'x' does not exist on type '{}'"

   but I expected to get different error like "Property 'toLowercase' does not exist on type 'string'" as was described in https://devblogs.microsoft.com/typescript/announcing-typescript-3-2/#objectdefineproperty-declarations-in-javascript
5. Ryan Cavanaugh (RyanCavanaugh)

   removed

   Experience EnhancementNoncontroversial enhancementsNoncontroversial enhancements

   on Jun 11, 2019
6. tokland commented on Oct 29, 2019

   

   Arnau Sanchez Sala (tokland)

   on Oct 29, 2019

   More actions

   Daniel Rosenwasser (@DanielRosenwasser) See #14650
7. DanielRosenwasser commented on Oct 29, 2019

   

   Daniel Rosenwasser (DanielRosenwasser)

   on Oct 29, 2019

   MemberAuthor

   More actions

   Arnau Sanchez Sala (@tokland) This is about JavaScript analysis, not TypeScript.

   👍React with 👍2Reacted by Arnau Sanchez Sala and Towry Wang
8. boneskull commented on Dec 8, 2020

   

   Christopher Hiller (boneskull)

   on Dec 8, 2020

   Contributor

   More actions

   I'm running in to this one. Anyone know of a workaround?
9. boneskull commented on Dec 8, 2020

   

   Christopher Hiller (boneskull)

   on Dec 8, 2020

   Contributor

   More actions

   n/m, workaround for above is something like this:

   // @ts-check
   
   class C {
     constructor() {
       /** @type {Readonly<string>} */
       this.x = undefined;
       Object.defineProperty(this, "x", { value: "hello" });
   
       this.x.toLowerCase();
     }
   }
10. akornatskyy commented on Dec 26, 2020

    

    Andriy Kornatskyy (akornatskyy)

    on Dec 26, 2020

    More actions

    You need to add definite assertion assignment to property 'x: string'.

    class C {
      x!: string;  // definite assertion
      constructor() {
        Object.defineProperty(this, 'x', {value: 'hello'});
        this.x.toLowerCase();
      }
    }

    👍React with 👍1Reacted by AimForNaN

    😕React with 😕2Reacted by Brian Kim and Ruben Bridgewater
11. brainkim commented on Feb 23, 2021

    

    Brian Kim (brainkim)

    on Feb 23, 2021

    More actions

    Andriy Kornatskyy (@akornatskyy) I think the source is assumed to be JavaScript in this issue and there is no definite assignment assertion syntax there as far as I can tell.
12. BridgeAR commented on Feb 20, 2025

    

    Ruben Bridgewater (BridgeAR)

    on Feb 20, 2025

    More actions

    I am running into this issue in a big code base as well. Could this be looked into again / is that something that could be added to a next roadmap Daniel Rosenwasser (@DanielRosenwasser)?