[Feature] make generated codes from enum could be minified when not used

Search Terms

For now TypeScript will transform enum from

enum Test {
    Key = 1
}

to

var Test;
(function (Test) {
    Test[Test["Key"] = 1] = "Key";
})(Test || (Test = {}));

This result is not friendly for uglyify or tree-shaking. When Test is not be used, the generated code block always remain as dead codes.

Suggestion

prefer to generate codes below:

var Test = /*#__PURE__*/(function () {
    var e = {}
    e[e["Key"] = 1] = "Key";
    return e
})();

Examples

The suggestion version will be removed.

Checklist

My suggestion meets these guidelines:

• This wouldn’t be a breaking change in existing TypeScript / JavaScript code
• This wouldn’t change the runtime behavior of existing JavaScript code
• This could be implemented without emitting different JS based on the types of the expressions
• This isn’t a runtime feature (e.g. new expression-level syntax)

[yordis]

Hey folks, any updates on this one?

We are changing most of the types to be union types because of tree-shaking issues, would appreciate some support on the topic.

[slavafomin]

This is indeed a very needed feature. We have a lot of packages and we are using enums extensively. Right now, all enums from all packages are getting added to the final application bundle, even if we are not using them at all, or using only a very small subset of all possible values.

I guess, one workaround would be to use constant enums instead, if possible.