ERR_UNKNOWN_FILE_EXTENSION on Node v20.0.0

[septs]

Search Terms

Node, ERR_UNKNOWN_FILE_EXTENSION

Expected Behavior

Fix it

Actual Behavior

see Minimal reproduction

Steps to reproduce the problem

see Minimal reproduction

Minimal reproduction

$ cat example.ts
console.log('example')
$ cat tsconfig.json
{ "ts-node": { "esm": true } }
$ npx ts-node example.ts
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /Users/septs/Projects/example/example.ts
    at new NodeError (node:internal/errors:399:5)
    at Object.getFileProtocolModuleFormat [as file:] (node:internal/modules/esm/get_format:99:9)
    at defaultGetFormat (node:internal/modules/esm/get_format:139:38)
    at defaultLoad (node:internal/modules/esm/load:83:20)
    at nextLoad (node:internal/modules/esm/hooks:781:28)
    at load (/Users/septs/.npm/_npx/1bf7c3c15bf47d04/node_modules/ts-node/dist/child/child-loader.js:19:122)
    at nextLoad (node:internal/modules/esm/hooks:781:28)
    at Hooks.load (node:internal/modules/esm/hooks:381:26)
    at handleMessage (node:internal/modules/esm/worker:153:24)
    at checkForMessages (node:internal/modules/esm/worker:102:28) {
  code: 'ERR_UNKNOWN_FILE_EXTENSION'
}

Specifications

• ts-node version: 10.9.1

• node version: 20.0.0

• TypeScript version: 5.0

• tsconfig.json:

  { "ts-node": { "esm": true } }

• package.json:

  {}

• Operating system and version: macOS 13.3.1

[septs]

microsoft/TypeScript#53922

---

Edited by 11/18/2023

Use tsx replace ts-node?

Or use ts-node@beta?

more see https://github.com/privatenumber/tsx, #2077

[csvn]

I have the same issue. I tried using --esm, { "esm": true } and --loader="ts-node/register", but got the ERR_UNKNOWN_FILE_EXTENSION no matter what I tried. Could not get ts-node to run on Node v20 with native ESM modules.

[Jack-Works]

FYI Node 20 has made a breaking change:

Custom ESM loader hooks run on dedicated thread
ESM hooks supplied via loaders (--experimental-loader=foo.mjs) now run in a dedicated thread, isolated from the main thread. This provides a separate scope for loaders and ensures no cross-contamination between loaders and application code.

https://nodejs.org/en/blog/release/v20.0.0

[RobinTail]

+1

The issue also appears when using the specially dedicated ESM runner

$ ts-node-esm file.ts

[neurolag]

I went forward and downgraded my node version to lts.
However, doing node --loader ts-node/esm {file} did work for me.

[wibed]

i expirience the same issue on:

# node --version
v18.16.0

EDIT:
my bad, i misinterpreted the gravity of the situation. manually enforcing the loader like this.

{
  "start": "npm run clean && cross-env NODE_ENV=development NODE_OPTIONS=\"--loader=ts-node/esm --trace-warnings\" webpack serve --mode=development --config webpack.config.ts",
}

worked out.

example sourced from here:
webpack/webpack-cli#2458

[RandivCosta]

i expirience the same issue on: Node v20,
I tried: $ node --loader ts-node/esm ./path
It worked for me but getting this warnning:
ExperimentalWarning: Custom ESM Loaders is an experimental feature and might change at any time