Open timocov opened 4 years ago
Reversed values for const enums are useless and cannot be accessed in the TS code, so why we should emit them?
I mean, that's 100% true of const enum
in general for both directions.
We created this flag because we found it very tiresome to do reverse lookups (from the value to the name) by hand in the debugger. I have to imagine other people are using it for the same reason and would be quite bothered by that scenario being broken.
Just as an use-case of using preserveConstEnum
and const enums: inside the project we don't to use just enums because they are "massive" and aren't inlined so we use const enums everywhere. In other hand we provide a library, which could be used in JS code, so we don't want "break" their code and tell our consumers to use magic constants instead. That's why we've enabled preserveConstEnum
- in the project we have inlined values, and in opposite we provide a way to use that enums in JS code.
Search Terms
preserveConstEnums, const enum, enum
Suggestion
By default all
const enum
s are preserved from output. One of the key differences ofconst enum
s is disallowing to looking up the reversed value:This means that we can't access const enum's "reversed" member even if
preserveConstEnums
flag is enabled.JS code of
const enum
with enabledpreserveConstEnums
is pretty similar to justenum
s right now and contains string literals (even they couldn't be accessed from the code):My feature request is change output of
const enum
s whenpreserveConstEnums
is enabled and strip "reversed" values from it:Note: actually tsc already has similar behaviour if you specify string constant value for every const enum's member, but the values are strings, not numbers - it is kind of workaround if your const enum is used to declare string constants.
Use Cases
Reversed values for const enums are useless and cannot be accessed in the TS code, so why we should emit them? 🤔 I guess in this case the behaviour of
const enum
s from types and from execution (JS) purposes will be the same.Checklist
My suggestion meets these guidelines: