ts-node cannot transpile on nodeJS 20

[wataruian]

Do you want to request a feature or report a bug?

I'm not sure if this is intended behavior or a bug

What is the current behavior?

When using ts-node with oclif, warning appears and the existing compiled source is executed instead
Warning: ts-node executable cannot transpile ESM in Node 20. Existing compiled source will be used instead.

This affects the development experience because you will need to compile in order to test existing code.

Will it be possible to use tsx instead of ts-node?

What is the expected behavior?

Able to transpile code in dev mode.

"@oclif/core": "^3.15.1"
Node: v20.10.0

[mdonnalley]

@wataruian Yep, this a warning we intentionally emit here

The TL;DR of it is that Node changed some things in v20 that broke how ts-node's esm loader was working. Because of that, we're not able to compile ESM at runtime when using node 20.

However it is possible to use tsx. You just need to replace the shebang in your bin/dev.js from ts-node to tsx
and everything should still work as expected. If you find any odd behavior using tsx - feel free to post a new issue or in this PR that's been hanging around for a while.

Here's a reading list in case you're curious:

• ./bin/dev.js throws ERR_UNKNOWN_FILE_EXTENSION on Node 20 core#817
• https://nodejs.org/en/blog/announcements/v20-release-announce#custom-esm-loader-hooks-nearing-stable
• ERR_UNKNOWN_FILE_EXTENSION on Node v20.0.0 TypeStrong/ts-node#1997

If it's okay with you, I'm going to close this issue since we already have an issue about ts-node + ESM + node 20 and there's a viable workaround - but please reopen it if you feel otherwise. Thanks!

[mdonnalley]

Just realized that the original oclif/core issue about this was closed. So I'm going to keep this one open and pin it since others are likely to run into this

[wataruian]

@mdonnalley, I am not sure how to make tsx work.

I tried to replace dev.js shebang with #!/usr/bin/env -S node --import tsx --no-warnings=ExperimentalWarning then I invoked with: yarn node bin/dev.js hello, I am getting error:

(node:50370) [ERR_UNKNOWN_FILE_EXTENSION] TypeError Plugin: my-cli: Unknown file extension ".ts" for /Users/wataruian/sample/packages/my-cli/src/commands/hello.ts

If I tried to invoke with yarn node --import tsx bin/dev.js hello, I am getting error:

node:internal/process/esm_loader:40
      internalBinding('errors').triggerUncaughtException(
                                ^
Error: Parse error @:4:49
    at Ge (file:///Users/wataruian/sample/.yarn/cache/tsx-npm-4.7.0-86d7b66640-3e6ee0a0a8.zip/node_modules/tsx/dist/index-bd1ceb03.mjs:10:8007)
    at Xe (file:///Users/wataruian/sample/.yarn/cache/tsx-npm-4.7.0-86d7b66640-3e6ee0a0a8.zip/node_modules/tsx/dist/index-bd1ceb03.mjs:15:66)
    at Ie (file:///Users/wataruian/sample/.yarn/cache/tsx-npm-4.7.0-86d7b66640-3e6ee0a0a8.zip/node_modules/tsx/dist/index-bd1ceb03.mjs:15:297)
    at Z (file:///Users/wataruian/sample/.yarn/cache/tsx-npm-4.7.0-86d7b66640-3e6ee0a0a8.zip/node_modules/tsx/dist/esm/index.mjs:5:1900)
    at async nextLoad (node:internal/modules/esm/hooks:865:22)
    at async Hooks.load (node:internal/modules/esm/hooks:448:20)
    at async MessagePort.handleMessage (node:internal/modules/esm/worker:196:18) {
  idx: 143
}

Am I doing something wrong?

[wataruian]

@mdonnalley

Update:

I was able to make tsx work via:

1. Update dev.js with tsx instead of node --import tsx/esm (I can't make this shebang work):

#!/usr/bin/env tsx --no-warnings=ExperimentalWarning

async function main() {
  const { execute } = await import('@oclif/core');
  await execute({ development: true, dir: import.meta.url });
}

await main();

2. Execute command via: yarn node --import tsx/esm bin/dev test-command

I am unsure if I did it clean enough or in best practice, but it works.

With this, I can compile the new code on the fly during dev mode which ts-node can't do in node:20

[mdonnalley]

Closing this since users can switch to tsx or bun (oclif/core#966) or use a different node version