ts-node: ERR_UNKNOWN_FILE_EXTENSION after adding "type": "module" to package.json

Node’s documentation has everything you need.

I am having the same issue:

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /Users/guoyunhe/Git/little-yellow-duck/src/cli.ts
    at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:71:15)
    at Loader.getFormat (internal/modules/esm/loader.js:102:42)
    at Loader.getModuleJob (internal/modules/esm/loader.js:231:31)
    at Loader.import (internal/modules/esm/loader.js:165:17)
    at Object.loadESM (internal/process/esm_loader.js:68:5)

However, "module": "commonjs" doesn’t work for me.

Typically you should have your tsconfig set to "module": "CommonJS" so that imports are compiled into commonjs calls. Then you don’t need to mess with node’s ESM loader. This is probably what you want: use "module": "CommonJS"

@realmayus let me know if this works or not.

after i added "type": "module", when run npm run dev, i got this

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: C:\Users\1\xxxx\next.config.js
require() of ES modules is not supported.

any solution? I am facing same problem

I tried to create a test file to test the structure of my typescript code.

test/index.ts

import Player from "../models/Player";

const testplayer = new Player();

When i executed it, i got this error:

import Player from "../models/Player";
^^^^^^

SyntaxError: Cannot use import statement outside a module

After a bit of research, I found this issue which suggested adding "type": "module" to the package.json. After I did this, i got the following error:

node:internal/process/esm_loader:74
    internalBinding('errors').triggerUncaughtException(
                              ^

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for XXX/test/index.ts

How can I run my file now? I am using ES6 (?) imports in the Player class: export default class Player {}

Specifications

• ts-node version: 9.1.0
• node version: 15.3.0
• TypeScript version: 4.1.2
• Operating system and version: macOS Catalina

use node --loader ts-node/esm ./my-script.ts instead ts-node ./my-script.ts

after i added "type": "module", when run npm run dev, i got this

Error [ERR_REQUIRE_ESM]: Must use import to load ES Module: C:\Users\1\xxxx\next.config.js
require() of ES modules is not supported.

https://github.com/TypeStrong/ts-node/tree/main/esm-usage-example

Node has restrictions about JSON files in ESM, maybe you’re hitting that.

@cspotcode. Could you kindly expound on this. Seems really interesting. And how can we mitigate this problem?

https://nodejs.org/api/esm.html#json-modules

Node has restrictions about JSON files in ESM, maybe you’re hitting that.

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension “.json” for D:\Installations\laragon\www\wp-pre-theme\wp-content\themes\firsttheme\package.json at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:71:15) at Loader.getFormat (internal/modules/esm/loader.js:102:42) at Loader.getModuleJob (internal/modules/esm/loader.js:231:31) at async ModuleWrap.<anonymous> (internal/modules/esm/module_job.js:58:21) at async Promise.all (index 10) at async link (internal/modules/esm/module_job.js:63:9) { code: ‘ERR_UNKNOWN_FILE_EXTENSION’

Thanks, that worked 👍