Error: unknown file extension .ts

[Thomas1664]

Expected Behavior

Load typescript files

Actual Behavior

When I try to execute a typescript file I get the following error message:
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /home/$USERNAME/$PATH_TO_DEV_FOLEDER/index.ts
at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15)
at Loader.getFormat (internal/modules/esm/loader.js:113:42)
at Loader.getModuleJob (internal/modules/esm/loader.js:243:31)
at Loader.import (internal/modules/esm/loader.js:177:17)

Steps to reproduce the problem

launch ts-node index.ts

Minimal reproduction

Specifications

• ts-node version: v8.10.2 (installed global)
• node version: v14.3.0
• TypeScript version:v3.9.3 (installed global)
• tsconfig.json, if you're using one:

{}

• Operating system and version: Windows 10 Version 2004
• If Windows, are you using WSL or WSL2?: Yes, Ubuntu 20.04 LTS in WSL2

[cspotcode]

ESM stuff? You might have better luck on our ESM thread. Or post a complete reproduction so someone else can debug.

[alexcochran]

I'm having the same issue.

λ npx ts-node src/app.ts
TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for C:\Users\$USER\$PATH_TO_DEV_FOLDER\src\app.ts
    at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15)
    at Loader.getFormat (internal/modules/esm/loader.js:113:42)
    at Loader.getModuleJob (internal/modules/esm/loader.js:243:31)
    at Loader.import (internal/modules/esm/loader.js:177:17)

[Aguinaldo-Alberto-Naldo]

Estou tendo o mesmo problema também

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for www\server\src\server.ts at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15) at Loader.getFormat (internal/modules/esm/loader.js:113:42) at Loader.getModuleJob (internal/modules/esm/loader.js:243:31) at Loader.import (internal/modules/esm/loader.js:177:17)

[cspotcode]

My earlier suggestion should point you in the right direction.

…

On Sun, Jun 21, 2020, 9:44 AM AguinaldoAlberto ***@***.***> wrote: Estou tendo o mesmo problema também TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for www\server\src\server.ts at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15) at Loader.getFormat (internal/modules/esm/loader.js:113:42) at Loader.getModuleJob (internal/modules/esm/loader.js:243:31) at Loader.import (internal/modules/esm/loader.js:177:17) — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#1062 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAC35OCO5M3WUUNXSLA4YS3RXYFCVANCNFSM4NOUHHYQ> .

[clinkadink]

Remove "type": "module" from package.json

[SaintPhill]

Remove "type": "module" from package.json

If remove module type, you cannot use imports in your .ts files

[Thomas1664]

I must disagree. In Angular projects, there is no "type": "module" in package.json and import synthax works fine. Try to set "module": "es2020" in tsconfig.json

[SaintPhill]

I must disagree. In Angular projects, there is no "type": "module" in package.json and import synthax works fine. Try to set "module": "es2020" in tsconfig.json

nope, same problem with import.
"Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension."

[Thomas1664]

I created a template repo which can be used by anyone who has trouble initializing ts-node.

[cspotcode]

Closing as this is not a ts-node bug. If you want to use node's native ESM support, which is currently experimental, then you can use ts-node's experimental ESM loader hook. See #1007 for details.

[paxperscientiam]

@clinkadink thanks, that did it for me

[cspotcode]

We've enabled the discussion forum for questions like this one.

https://github.com/TypeStrong/ts-node/discussions

We're trying to keep the issue tracker limited to actionable tasks, so contributors can focus on making fixes and improvements to ts-node.

Since this is not a bug and nothing needs to change in ts-node, it's not actionable, so it was closed. Discussions, on the other hand, are the perfect place to ask advice, share guides, and help with project configuration.

Another good thing about the discussion forum: you don't need to fill out an issue template.

[a-h]

This stack overflow answer helped me: https://stackoverflow.com/questions/63445821/ts-node-execute-typescript-with-module-import-and-module-defined

Updating my tsconfig.json to migrate from "module": "es6" to "module": "commonjs" allowed me to run my TypeScript file.

[kseebrinegar]

@a-h Thank you bro! you the man!

[buzuosheng]

Remove "type": "module" from package.json

If remove module type, you cannot use imports in your .ts files

I'm having the same issue. how to fix, thx

[itcat99]

This stack overflow answer helped me: https://stackoverflow.com/questions/63445821/ts-node-execute-typescript-with-module-import-and-module-defined

Updating my tsconfig.json to migrate from "module": "es6" to "module": "commonjs" allowed me to run my TypeScript file.

Thanks! it's useful.

[Rollingegg]

From #1007, use node --loader ts-node/esm ./my-script.ts if your tsconfig.json contains "module": "commonjs"

[shanoysinc]

I remove type: module from package json and it work

[Abeautifulsnow]

This stack overflow answer helped me: https://stackoverflow.com/questions/63445821/ts-node-execute-typescript-with-module-import-and-module-defined

Updating my tsconfig.json to migrate from "module": "es6" to "module": "commonjs" allowed me to run my TypeScript file.

This solution resolves my two problems which are "import" syntax-error outside module and unknown file extensions ".ts"!!! Thank you very much for saving my time. 😁

[iway1]

Add this to the tsconfig.json:

  "compilerOptions": {
    "esModuleInterop": true
  }

and make sure to start the server with ts-node:

ts-node my_ts_node_server.ts

It is crazy how hard it was for me to find this. This will allow you to use imports as well as use typescript.

[Mehak-Mehta]

Add this to the tsconfig.json:

  "compilerOptions": {
    "esModuleInterop": true
  }

and make sure to start the server with ts-node:

ts-node my_ts_node_server.ts

It is crazy how hard it was for me to find this. This will allow you to use imports as well as use typescript.

Yup that works!!

[Cobular]

From #1007, use node --loader ts-node/esm ./my-script.ts if your tsconfig.json contains "module": "commonjs"

Real quick follow up to this - running with this makes my code ~8x slower than ts-node by itself with changed options or just using tsc and node, and that's testing the same exact function 10 times in a loop to mitigate the effects of the typescript JIT compilation times. Hopefully this is useful to someone?

[goldEli]

Remove "type": "module" from package.json

If remove module type, you cannot use imports in your .ts files

set the value of module to commonjs in tsconfig.json, it works for me.

{
"module": "commonjs",  
}

[iseekTo]

ts-node --skip-project scripts/yourFile.ts

[karlhorky]

For anyone who is running into this issue on CI or on Node.js 16.12.0, it seems like this latest version has made some changes to the hooks API 😱

https://github.com/nodejs/node/releases/tag/v16.12.0

Also mentioned here:

#1007 (comment)

[cspotcode]

Supported by ts-node 10.3.1

[retrotechie]

Solution 1:

Remove "type": "module" in package.json

Solution 2:

package.json

...
"type": "module"
...

tsconfig.json

"compilerOptions": {
...
"module": "ESNext",
...
},
"ts-node": {
  "esm": true
}

I'm not sure if we had better solutions but these worked for me.

[rtritto]

This change should help/fix (it's released in Node v19.6.0 and there is a backport to v18).

Another related/workaround is ts-import.

[xgqfrms]

ts-node error ❌

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts"

ESM solution ✅

"type": "module", & ts-node-esm

{
  "name": "patch-package-in-action",
  "version": "1.0.0",
  "description": "patch-package in action",
  "main": "./src/app.ts",
  "type": "module",
  "scripts": {
    "app-esm": "npx ts-node-esm ./src/app.ts",
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/web-fullstack/patch-package-in-action.git"
  },
  "author": "xgqfrms",
  "license": "MIT",
  "dependencies": {
    "lodash-es": "^4.17.21",
    "typescript": "^5.0.2"
  },
  "devDependencies": {
    "@types/lodash-es": "^4.17.7",
    "app-node-env": "^1.4.7",
    "rimraf": "^4.4.0",
    "ts-node": "^10.9.1"
  }
}

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "esModuleInterop": true,
    "forceConsistentCasingInFileNames": true,
    "strict": true,
    "skipLibCheck": true
  }
}

lodash-es

// ./src/app.ts

import {toString} from "lodash-es";

type Obj = {
  [key: string]: any;
}

const obj: Obj = {
  name: 'xgqfrms',
  country: 'China',
  language: 'zh-hans',
};

const str = toString(obj);
console.log(`toString =`, str1);

refs

https://typestrong.org/ts-node/docs/imports/

[leonasdev]

I just rm -rf dist and tsc & node dist/index.js again, then it works.

[VladBrok]

What worked for me is ts-node --esm <filename>. No esModuleInterop or package.json changes

@dfenerski thanks

[neerajkumar161]

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

This worked for me. Thanks, @retrotechie 🚀

[JuYiYang]

Remove "type": "module" from package.json
remain invalid

[88brmig]

if your tsconfig.json contains "module": "ESNext". I have used the below script in my package.json. It worked.

 "start": "nodemon -e ts -w ./src -x npm run watch:serve",
 "watch:serve": "node --loader ts-node/esm src/server.ts",

Using node 20 with sveltekit, this works

[JuYiYang]

if your tsconfig.json contains "module": "ESNext". I have used the below script in my package.json. It worked.

 "start": "nodemon -e ts -w ./src -x npm run watch:serve",
 "watch:serve": "node --loader ts-node/esm src/server.ts",

Using node 20 with sveltekit, this works

if your tsconfig.json contains "module": "ESNext". I have used the below script in my package.json. It worked.

 "start": "nodemon -e ts -w ./src -x npm run watch:serve",
 "watch:serve": "node --loader ts-node/esm src/server.ts",

Using node 20 with sveltekit, this works

if your tsconfig.json contains "module": "ESNext". I have used the below script in my package.json. It worked.

 "start": "nodemon -e ts -w ./src -x npm run watch:serve",
 "watch:serve": "node --loader ts-node/esm src/server.ts",

Using node 20 with sveltekit, this works

if your tsconfig.json contains "module": "ESNext". I have used the below script in my package.json. It worked.

 "start": "nodemon -e ts -w ./src -x npm run watch:serve",
 "watch:serve": "node --loader ts-node/esm src/server.ts",

Using node 20 with sveltekit, this works

Thank you😘

[jhonatanAlanFerreira]

I need "type": "module" in package.json
npx tsx ./file.ts worked for me

[quantuminformation]

same error in 2023

anyone code a tsx launch file for vscode that allows debugging?

[arsinclair]

If you suddenly started getting this issue, this might be the cause: #2094

[ejas404]

Add this to the tsconfig.json:

  "compilerOptions": {
    "esModuleInterop": true
  }

and make sure to start the server with ts-node:

ts-node my_ts_node_server.ts

It is crazy how hard it was for me to find this. This will allow you to use imports as well as use typescript.

Remove "type": "module" from package.json

If remove module type, you cannot use imports in your .ts files

for using esm add these
"compilerOptions": {

"module": "CommonJS",                                
"esModuleInterop": true,

}

it worked for me
if you face importing .ts extension

add this to your compilerOptions
"allowImportingTsExtensions": true,

Nb : Option 'allowImportingTsExtensions' can only be used when either 'noEmit' or 'emitDeclarationOnly' is set.ts
you have to set one of the true with it

[arsinclair]

for using esm add these

"module": "CommonJS",

That's not true. ESM and CJS (CommonJS) are two different things, changing module to CommonJS will make tsc produce CommonJS code.

[jamesrr39]

I got this same error (Unknown file extension ".ts"), trying to run a typescript script with ts-node 10.9.1 and Node 20.10. I couldn't find a solution unfortunately (I tried "esModuleInterop": true in tsconfig), but running the script through tsx worked, so I ended up migrating from ts-node to tsx.

I find it really odd that .ts files are not recognised by default. Surely ts-node should know how to handle .ts files?

[Rush]

This is what worked for me. Not even ts-node-esm worked.

node --experimental-specifier-resolution=node --loader ts-node/esm file.ts

Let me just say that the entire ESM situation in Node.JS is a catastrophe. It created so much pain, incompatibility, lost hours. I don't understand why some decisions were made that contributed to this pain. It's probably not as bad as Python2 and Python3 but very close!

[C0D3O]

for me worked the opposite ( updated node to the latest 21.x version )
the ts-node config part in tsconfig.json

"ts-node": {
		"esm": false,
		"compilerOptions": {
			"module": "NodeNext"
		}
	},

[eminoda]

tsconfig.json

{
  "compilerOptions": {
    "module": "ESNext", // tell tsc complier use esm module
    "moduleResolution": "Node10", // find file use CommonJS require
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "outDir": "dist"
  },
  "include": ["src/**/*"]
}

package.json

"type": "module",

[hellznrg]

I got this same error (Unknown file extension ".ts"), trying to run a typescript script with ts-node 10.9.1 and Node 20.10. I couldn't find a solution unfortunately (I tried "esModuleInterop": true in tsconfig), but running the script through tsx worked, so I ended up migrating from ts-node to tsx.

I find it really odd that .ts files are not recognised by default. Surely ts-node should know how to handle .ts files?

Switching to tsx was the only thing that worked for me. Now it's as simple as yarn tsx . and BOOM. Not sure what the problem with ts-node is. It's defintely a ts-node problem.