const enums not supported in some transpilers

[moltar]

Describe the Bug

Version appears to be undefined.

Steps to Reproduce

import { CloudEvent, Version } from 'cloudevents'

new CloudEvent({
      id: event.id.toString(),
      source: event.source,
      type: event.type,
      subject: event.subject,
      time: event.time,
      data: event.data,
      specversion: Version.V03,
})

Expected Behavior

Version should be defined.

Additional context

Using package from NPM version 3.1.0.

[moltar]

Never mind, seems to be an issue with @swc-node/jest.

[moltar]

See swc-project/swc#940

Maybe this can refactored from enum to const as const approach?

const Versions  = {
  V03: 3,
} as const

[lance]

Hi @moltar - I am unable to reproduce this. I tried downloading the swc CLI, and ran it on src/event/cloudevent.ts where the Version enum is declared, and did not get any errors. It produced this transpiled JS:

export var Version;
(function(Version1) {
    Version1["V1"] = "1.0";
    Version1["V03"] = "0.3";
})(Version || (Version = {
}));

Can you provide some steps to reproduce this?

[moltar]

Here is a repro: https://github.com/moltar/cloudevent-exp

[lance]

Thanks @moltar. This really seems to be an issue with swc. By modifying your example to use ts-jest instead of swc the example runs without error.

 npm t

> cloudevent-exp@1.0.0 test /home/lanceball/src/github.com/tmp/cloudevent-exp
> jest

 PASS  ./cloudevents.test.ts
  Version
    ✓ should work (2 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        2.39 s
Ran all test suites.

My modifications.

• package.json

diff --git a/package.json b/package.json
index 2342abf..fa3a0b7 100644
--- a/package.json
+++ b/package.json
@@ -11,10 +11,12 @@
   "license": "ISC",
   "dependencies": {
     "@swc-node/jest": "0.1.27",
-    "cloudevent": "0.6.0",
     "cloudevents": "3.1.0",
     "jest": "26.4.2",
-    "ts-jest": "26.3.0",
-    "typescript": "4.0.2"
+    "typescript": "^4.0.2"
+  },
+  "devDependencies": {
+    "@types/jest": "^26.0.12",
+    "ts-jest": "^26.3.0"
   }
 }

• jest.config.js

diff --git a/jest.config.js b/jest.config.js
index 0bda6ad..91a2d2c 100644
--- a/jest.config.js
+++ b/jest.config.js
@@ -1,11 +1,4 @@
 module.exports = {
+  preset: 'ts-jest',
   testEnvironment: 'node',
-
-  // config for ts-jest
-  // preset: 'ts-jest',
-
-  // config for @swc-node/jest
-  transform: {
-    '^.+\\.(t|j)sx?$': ['@swc-node/jest'],
-  },
 };

[moltar]

It is an issue with SWC, and they did confirm it in the linked issue: swc-project/swc#940

But this is also a larger issue, because Babel also does not support const enums: babel/babel#8741

I don't use babel, but there is a large portion of TS users who do.

Here is a short explainer (not my article): https://ncjamieson.com/dont-export-const-enums/

[github-actions]

This issue is stale because it has been open 30 days with no activity.

[moltar]

Not stale

[github-actions]

This issue is stale because it has been open 30 days with no activity.

[moltar]

https://blog.benwinding.com/github-stale-bots/

https://news.ycombinator.com/item?id=25821092

[lance]

@moltar I see your point to some degree (though the blog post you linked is 404), which is why we have modified the bot to never actually close an issue. But having the label is useful, imo.

[github-actions]

This issue is stale because it has been open 30 days with no activity.