[russellsprouts]

const enums are one of the few cases where type information changes the emitted JS, something that's arguably a bigger problem than TypeScript-specific, but still just syntax sugar, syntax highlighted in the article.

Const enums are erased at compile time. If you have a reference to `MyEnum.VAR`, TS has to check whether the enum is a const enum, and if so, replace with something like `1 /* VAR */`. This means that the type information in one file (where the enum is defined) is necessary to determine the proper output of any file that uses it.

[ragnese]

Thank you for the answer! I won't waste your time because I'm sure the answer is somewhere on the web, but off the top of my head, I don't understand why TS "has" to emit different JS. I would've assumed that the entire point of a const enum is to inline the raw value in the emitted JS, and thus, the programmer should be careful to remember/know that the code is dealing with raw ints/strings.

[russellsprouts]

You potentially get a problem for every '.' expression. In this code:

  import {Something} from './file';
  console.log(Something.PROP);

TypeScript doesn't know what to emit without type information. If Something is a class, then the JS will look the same. But if it's a const enum, then TypeScript has to erase the Something.PROP expression and replace it with the constant value of that enum member, since Something will not exist at runtime.