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