Typescript const enums not compiled correctly

[jestarray]

Version

3.3.0

Reproduction link

https://github.com/jestarray/const-enum-vue

Environment info

   @vue/babel-helper-vue-jsx-merge-props:  1.0.0-beta.2
    @vue/babel-plugin-transform-vue-jsx:  1.0.0-beta.2
    @vue/babel-preset-app:  3.3.0
    @vue/babel-preset-jsx:  1.0.0-beta.2
    @vue/babel-sugar-functional-vue:  1.0.0-beta.2
    @vue/babel-sugar-inject-h:  1.0.0-beta.2
    @vue/babel-sugar-v-model:  1.0.0-beta.2
    @vue/babel-sugar-v-on:  1.0.0-beta.2
    @vue/cli-overlay:  3.3.0
    @vue/cli-plugin-babel: ^3.3.0 => 3.3.0
    @vue/cli-plugin-typescript: ^3.3.0 => 3.3.0
    @vue/cli-service: ^3.3.0 => 3.3.1
    @vue/cli-shared-utils:  3.3.0
    @vue/component-compiler-utils:  2.5.1
    @vue/preload-webpack-plugin:  1.1.0
    @vue/web-component-wrapper:  1.2.0
    babel-helper-vue-jsx-merge-props:  2.0.3
    babel-plugin-transform-vue-jsx:  4.0.1
    vue: ^2.5.21 => 2.5.22
    vue-class-component: ^6.0.0 => 6.3.2
    vue-hot-reload-api:  2.3.1
    vue-loader:  15.6.2
    vue-property-decorator: ^7.0.0 => 7.3.0
    vue-style-loader:  4.1.2
    vue-template-compiler: ^2.5.21 => 2.5.22
    vue-template-es2015-compiler:  1.8.2
  npmGlobalPackages:
    @vue/cli: 3.3.0

Steps to reproduce

-npm install the dependencies,
-npm run build
-check the output in dist

What is expected?

const enum declarations should be inlined.
example:

const enum TEST{
HELLLO
}

console.log(TEST.HELLO);
//should be transpiled to console.log(0)

What is actually happening?

It's transpiled into console.log(TEST.HELLO) instead.

---

I have a const enum of keyboard events and event key names that I need inlined correctly. Followed some solutions of ts-loader since vue cli uses it under the hood but no luck.

[jestarray]

microsoft/TypeScript#10879 (comment)

Alright, managed to fix , this had to be added to tsconfig :
"isolatedModules": false /* Transpile each file as a separate module (similar to 'ts.transpileModule').
question remains if you guys want it as default for tsconfig. Otherwise, feel free to close.

[yoyo930021]

microsoft/TypeScript#16671

[ryannmedina]

Hi @jestarray! I ran into a similar issue this last week and this thread was helpful.

We ended up separating our enum "types" into a different file. (a plain .ts file) Then we imported that file into our types file. It fixed the problem. Here's a watered down version:

types.d.ts

// Import Enums
import { MyEnum } from './enums'

export interface MyInterface {
   firstProperty: MyEnum,
   secondProperty: string,
   thirdProperty: number 
}

enums.ts

export enum MyEnum {
   firstProperty = 0,
   secondProperty = 1,
   thirdProperty = 2 
}

That was suggested by Lukas Behal.