ERR_UNKNOWN_FILE_EXTENSION after adding "type": "module" to package.json

[realmayus]

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

[cspotcode]

Are you following the instructions from here? #1007

node forces a different style of registration to hook into the ESM loader. So if you choose to use node's ESM loader, you'll also need to use this new style of registration with ts-node. If we're not registered correctly, then we have no way of resolving and compiling your .ts files.

[cspotcode]

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.

[realmayus]

Thanks, that worked 👍

[guoyunhe]

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.

[cspotcode]

@guoyunhe check this out
#1171 (comment)

[buzuosheng]

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

[guoyunhe]

@guoyunhe check this out
#1171 (comment)

I tried but no luck.

[buzuosheng]

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.

[sodhisaab]

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

[lovetingyuan]

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

[AhmadRaza9]

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. (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'

[cspotcode]

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

[AhmadRaza9]

I have no idea, i can't understand 😒

[bishop254]

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?

[cspotcode]

Node's documentation has everything you need.

[CSchulz]

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