TypeScript - ReferenceError: Can't find variable when using a declared enum

[splintor]

Take a look at the following TypeScript code:

/// <reference path='../../../../typings/karma-jasmine/karma-jasmine.d.ts' />
declare module MyModule{
    export enum MyEnum{
        First = 1,
        Second = 2,
        Third = 3,
    }
}

describe("wallaby test", () => {
    it("should test TypeScript enums", () => {
        var a = MyModule.MyEnum.First;
        expect(a).toBe(1);
    });
});

Wallaby show an error on this code which says:
ReferenceError: Can't find variable: MyModule

This seems to be a problem with the declare module statement, as replacing it with module (with no declare) makes the problem go away, but this is the way the enum is declared in the d.ts file we are using.

[ArtemGovorov]

I may be missing something but TypeScript declarations are not generated into JavaScript, so the JavaScript for your example looks like this and MyModule is not there, so the same error would happen.

Is it working for you without wallaby? If so, would it be possible to create a working sample, perhaps a sample Github repository so I could have a look?

[splintor]

There seems to be a difference between the online compiler (and the npm typescript version 1.5.0-beta compiler) and my tsc.exe compiler (version 1.0.3.0).

See this simple code:

declare module MyModule{
    export enum MyEnum{
        First = 1,
        Second= 2,
        Third = 3,
    }
}

function test() {
    return MyModule.MyEnum.First;
}

The online compiler (and npm typescript compiler) transpiles it to:

function test() {
    return MyModule.MyEnum.First;
}

But when I run it with tsc, I get this js file generated:

function test() {
    return 1 /* First */;
}

What workaround can I use, provided that I can't really change my d.ts file?

[ArtemGovorov]

I'll have a look why it happens, in a meantime, as a workaround, you may use bootstrap function where you may define the enum like:

bootstrap: function (wallaby) {
  MyModule = MyModule || {};
  MyModule.MyEnum = MyModule.MyEnum || {};
  MyModule.MyEnum.First = 1;
  MyModule.MyEnum.Second = 2;
  // etc
}

[ArtemGovorov]

It is indeed the difference between typescript compilers.

v1.4 replaces MyModule.MyEnum.First with 1 and v1.5 beta doesn't. Wallaby.js is using the latest, so that's why it happens.

[ArtemGovorov]

Created the issue in TypeScript repo.

[splintor]

Thanks.
It seems using export const enum works OK. I'll try to see if I can change my d.ts file to use const enum.

[ArtemGovorov]

So as it looks like const enum is the recommended way and it works, closing the issue.