529

When I try to start my app on Heroku I got the following stack trace. It is just a basic ts.app like you see with ts-node and nodemon.

I am really interested in what the answer is going to be.

2020-05-30T00:03:12.201106+00:00 heroku[web.1]: Starting process with command `npm start`
2020-05-30T00:03:14.405285+00:00 app[web.1]: 
2020-05-30T00:03:14.405303+00:00 app[web.1]: > [email protected] start /app
2020-05-30T00:03:14.405303+00:00 app[web.1]: > ts-node src/App.ts
2020-05-30T00:03:14.405304+00:00 app[web.1]: 
2020-05-30T00:03:14.833655+00:00 app[web.1]: (node:23) ExperimentalWarning: The ESM module loader is experimental.
2020-05-30T00:03:14.839311+00:00 app[web.1]: TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".ts" for /app/src/App.ts
2020-05-30T00:03:14.839312+00:00 app[web.1]:     at Loader.defaultGetFormat [as _getFormat] (internal/modules/esm/get_format.js:65:15)
2020-05-30T00:03:14.839314+00:00 app[web.1]:     at Loader.getFormat (internal/modules/esm/loader.js:113:42)
2020-05-30T00:03:14.839315+00:00 app[web.1]:     at Loader.getModuleJob (internal/modules/esm/loader.js:244:31)
2020-05-30T00:03:14.839315+00:00 app[web.1]:     at processTicksAndRejections (internal/process/task_queues.js:97:5)
2020-05-30T00:03:14.839316+00:00 app[web.1]:     at Loader.import (internal/modules/esm/loader.js:178:17)
2020-05-30T00:03:14.847801+00:00 app[web.1]: npm ERR! code ELIFECYCLE
2020-05-30T00:03:14.847998+00:00 app[web.1]: npm ERR! errno 1
2020-05-30T00:03:14.848957+00:00 app[web.1]: npm ERR! [email protected] start: `ts-node src/App.ts`
2020-05-30T00:03:14.849050+00:00 app[web.1]: npm ERR! Exit status 1
2020-05-30T00:03:14.849172+00:00 app[web.1]: npm ERR! 
2020-05-30T00:03:14.849254+00:00 app[web.1]: npm ERR! Failed at the [email protected] start script.
2020-05-30T00:03:14.849337+00:00 app[web.1]: npm ERR! This is probably not a problem with npm. There is likely additional logging output above.
2020-05-30T00:03:14.854859+00:00 app[web.1]: 
2020-05-30T00:03:14.854998+00:00 app[web.1]: npm ERR! A complete log of this run can be found in:
2020-05-30T00:03:14.855069+00:00 app[web.1]: npm ERR!     /app/.npm/_logs/2020-05-30T00_03_14_850Z-debug.log
2020-05-30T00:03:14.907689+00:00 heroku[web.1]: Process exited with status 1
2020-05-30T00:03:14.943718+00:00 heroku[web.1]: State changed from starting to crashed

This is my package.json:

{
   "name": "discordtoornamentmanager",
   "version": "1.0.0",
   "description": "",
   "main": "dist/app.js",
   "type": "module",
   "scripts": {
      "test": "echo \"Error: no test specified\" && exit 1",
      "dev": "nodemon -x ts-node src/App.ts",
      "start": "ts-node src/App.ts"
   },
   "keywords": [],
   "author": "",
   "license": "ISC",
   "dependencies": {
      "@types/node": "^14.0.5",
      "axios": "^0.19.2",
      "discord.js": "^12.2.0",
      "pg": "^8.2.1",
      "reflect-metadata": "^0.1.10",
      "typeorm": "0.2.25",
      "typescript": "^3.9.3",
      "nodemon": "^2.0.4",
      "ts-node": "8.10.1"

   }
}

And this is my tsconfig:

{
   "compilerOptions": {
      "lib": [
         "es6"
      ],
      "target": "es6",
      "module": "commonjs",
      "moduleResolution": "node",
      "outDir": "dist",
      "resolveJsonModule": true,
      "emitDecoratorMetadata": true,
      "esModuleInterop": true,
      "experimentalDecorators": true,
      "sourceMap": true
   },
   "include": ["src/**/*.ts"],
   "exclude": ["node_modules", "**/*.spec.ts"]
}
3
  • Lots of people are facing this issue stackoverflow.com/questions/65097694/…
    – giorgio79
    Commented Apr 22, 2021 at 18:15
  • 10
    It is way way down in the answers list but in 2023 tsx seems to just work whereas ts-node gets bogged down in experimental features and even then often won't work. Commented Sep 1, 2023 at 10:13
  • 3
    @Elizar Pongracz Would you consider accepting my answer below to use tsx since this is the only option that works well in 2023. Helpful for other developers to save a ton of time with just this small action
    – wongx
    Commented Nov 2, 2023 at 20:06

33 Answers 33

550

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


https://github.com/TypeStrong/ts-node/issues/935

https://github.com/TypeStrong/ts-node/issues/1007#issuecomment-1163471306


If you don't want to remove "type": "module" (for example if you're using import statements in your .ts which allows the inference of types from modules), then you can use the following option in tsconfig.json:

{
  "compilerOptions": {
    "esModuleInterop": true,
  }
}

And then you can start the server with the config using ts-node.

Install:

npm install -g ts-node

Run:

ts-node-esm my_server.ts
30
  • 215
    Removing "type": "module" gives me To load an ES module, set "type": "module" in the package.json for a script I use import { ... } form '../' in. Commented Jan 31, 2021 at 23:31
  • 13
    @DanDascalescu, you are right. Unfortunately, it's not possible to use ESM without "type": "module". The described solution works because the author mentioned: "module": "commonjs" in his tsconfig.json :) otherwise, you can try hop into 1007
    – vadimk7
    Commented Feb 1, 2021 at 6:47
  • 19
    @wormsparty exactly! I'm still in it Commented Apr 4, 2021 at 7:36
  • 246
    "esModuleInterop": true is already there in tsconfig file, still getting this error.
    – Shiv
    Commented Aug 12, 2021 at 15:58
  • 62
    Try running ts-node with the --esm flag. That fixed the ERR_UNKNOWN_FILE_EXTENSION error for me. I'm using Node 16.15.1 btw. ex: ts-node --esm myfile.ts
    – joelwat
    Commented Jun 10, 2022 at 23:42
492
+100

In my opinion, this answer is best. https://stackoverflow.com/a/74608156/12894626

tldr; After years of trying to make ts-node work, just use tsx which works out of the box.

npm i -D tsx
npx tsx src/index.ts

npm: https://www.npmjs.com/package/tsx

  • Has 400k weekly downloads at the time of writing and rising.
21
  • 50
    I was literally about to cry because I couldn't get my stuff to build during an all-nighter before a major deadline. This saved my day big time!! Thanks!
    – lordphnx
    Commented Jul 3, 2023 at 20:01
  • 10
    easily the best answer here. I tried them all and imo tsx is just as supported as a community package than anything else and works right out of the box. this is what OP wanted and this provides that. ts-node will always require mucking around with your package type and ESM related stuff.
    – Johnny
    Commented Sep 14, 2023 at 18:21
  • 16
    Only answer that worked for me, no other solution made any difference (remove/add "type":"mode" or whatever, use ts-node config or config nodemon execMap, etc, etc, etc). It's just pathetic a thing made to read typescript files emits an error message saying .ts is an unknown file extension!
    – S4NR-3000
    Commented Oct 10, 2023 at 2:02
  • 19
    2023 way to go.
    – friartuck
    Commented Nov 9, 2023 at 12:14
  • 14
    2024, this is the way !
    – Thaldath
    Commented Jan 19 at 15:27
252

use

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

// OR

ts-node --esm ./my-script.ts

instead of

ts-node ./my-script.ts
14
  • 11
    what is ts-node/esm? No description at github.com/bluelovers/ws-esm-ts-node
    – giorgio79
    Commented Apr 20, 2021 at 8:01
  • 3
    more info is here https://github.com/TypeStrong/ts-node/issues/1007
    – buzuosheng
    Commented Apr 21, 2021 at 11:43
  • 9
    To run it with nodemon we can use environment variables. The call could then look something like this : NODE_OPTIONS='--no-warnings --loader ts-node/esm' nodemon --watch 'src/**/*' -e ts,tsx --exec ts-node ./server.ts Commented Apr 24, 2021 at 20:36
  • 7
    Why does this work? Commented Dec 17, 2021 at 3:41
  • 19
    You can also use ts-node --esm ./my-script.ts
    – abraj
    Commented Mar 12, 2022 at 11:24
137

MARCH 2022

USING: Node 16.6.2, ts-node v 10.7.0

What worked for me was having "type": "module" in package.json, and adding:

node --experimental-specifier-resolution=node --loader ts-node/esm ./src/app.ts

tsconfig.json:

{
    "compilerOptions": {
      "module": "ESNext",
      "esModuleInterop": true,
      "target": "ESNext",
      "moduleResolution": "Node",
      "outDir": "dist",
      "forceConsistentCasingInFileNames": true,
      "noFallthroughCasesInSwitch": true,
      "isolatedModules": false,
      "strict": true,
      "noImplicitAny": true,
      "useUnknownInCatchVariables": false,
      "inlineSourceMap": true
    },
    "ts-node": {
        "esm": true
    },
    "lib": ["esnext"]
}

Credits to @FelipePlets for the useful answer here

EDIT You may want to use a non-esnext option, as per the ts docs:

The special ESNext value refers to the highest version your version of TypeScript supports. This setting should be used with caution, since it doesn’t mean the same thing between different TypeScript versions and can make upgrades less predictable.

3
  • 42
    Thes ts-node: esm: true did it for me 👍 thanks.
    – CTS_AE
    Commented Apr 5, 2022 at 10:30
  • thanks for the tsconfig. however I did not need to use any experimental option. I used npmjs.com/package/ts-init however. Commented May 23, 2022 at 15:28
  • echoing @CTS_AE — I've added "ts-node": {"esm": true} to tsconfig.json, and "type": "module" to package.json — now I have top-level await in my TypeScript, with import './dependency.ts, and can run the file using ts-node file.ts!
    – alxndr
    Commented Jun 25 at 22:57
93

Removing "type": "module" from package.json and adding:

  "compilerOptions": {
    "module": "CommonJS"
  },

In tsconfig.json fixed this for me.

6
  • 3
    This solved my issue. I use Next.js + Express with TypeScript. Changed the "esnext" to "commonJS" from the "module" in tsconfig.json. Everything still works fine, I don't know whether there will be any break or not.
    – Sena
    Commented Oct 13, 2021 at 3:06
  • 73
    SyntaxError: Cannot use import statement outside a module
    – Phil
    Commented Jan 1, 2022 at 12:55
  • 2
    While it would seem to make no sense, in my particular case with this settings I can successfully run code with ES6 Import statements without any issue using ts-node. Commented Jan 5, 2022 at 23:12
  • 2
    so what's the benefit of using module = es2020? or how would it work? I can't seem to find a way to make it work Commented Apr 6, 2022 at 23:00
  • I'm on a similar situation as "Sena", i'm also using Next.js and had to do that in order to run scripts locally and leverage the other .ts files in my repo.
    – kroe
    Commented Dec 25, 2022 at 18:13
84

Solution One

  1. Remove "type": "module" from package.json if it's added
  2. In tsconfig.json under the compilerOptions Set module property to CommonJS module: "CommonJS" and moduleResolution: "Node"

Solution Two

if the first one didn't work, or you have for some reason to keep module: "ESNext"

1- Add "type": "module" to package.json

2- Install ts-node npm i -g ts-node

3- Go to tsconfig.json and add the following:

{
    "compilerOptions": {
        "module": "ESNext",
        "moduleResolution": "Node",
        /* ... your props ... */
    },
    "ts-node": {
        "esm": true
    }
}

4- Run ts-node fileName.ts

7
  • 2
    2- Install ts-node npm i -g ts-node OR: use npx ts-node path/to/file.ts for locally installed ts-node
    – besthost
    Commented Apr 26, 2022 at 10:05
  • 2
    Thank you. Solution 2 worked for me. Missing point in the other answers is that installing "ts-node" step. Commented May 26, 2022 at 16:14
  • 2
    Solution 2 works as of June 2022 Commented Jun 27, 2022 at 20:03
  • 2
    Solution 2 is the best
    – Jeanno
    Commented Aug 4, 2022 at 5:01
  • 5
    Still seeing unknown filename .ts after these (soln 2) steps. Everything is installed. Commented Jul 19, 2023 at 20:52
45

Try adding this to your tsconfig.json

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

I was able to fix with a tsconfig.json that looked something like:

{
  "compilerOptions": {
    "target": "es2022",
    "lib": ["ES2022"],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "strict": true,
    "forceConsistentCasingInFileNames": true,
    "noFallthroughCasesInSwitch": true,
    "module": "ES2022",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
  },
  "exclude": [
    "node_modules",
  ],
  "ts-node": {
    "esm": true,
    "experimentalSpecifierResolution": "node",
  }
}
2
  • 5
    Adding "experimentalSpecifierResolution": "node" fixed it for me. Thanks.
    – mrvautin
    Commented May 4, 2023 at 7:49
  • 1
    Adding "module": "ES2022" (instead of "module": "commonjs") worked for me, thanks!
    – jbmilgrom
    Commented Oct 1, 2023 at 18:29
25

I first came across this problem probably over a year ago, and ts-node has yet to fix it. None of the above solutions worked for me, and I have seemingly tried everything.

I just resorted to using tsc --outDir out file.ts and then running the file normally with node out/file.js, and then adding out to the .gitignore.

The thought behind ts-node is wonderful, just really sucks when it can't handle seemingly straightforward examples like this. Apologies the solution doesn't use ts-node, but I couldn't get it to work.

2
  • This I think would be the better "manual" solution, compiling the file to js and then run it Commented May 6, 2022 at 8:12
  • Of course make sure not to have "type": "module" in package.json Commented May 6, 2022 at 8:25
18

I made some changes on my package.json & tsconfig.json.Finally, it worked for me!

  1. Add "type": "module" to package.json
  2. Uncomment "moduleResolution": "node" section in your tsconfig.json
  3. Change "module" section to "ESNEXT" in your tsconfig.json
  4. Then Just Run the main script with this node --loader ts-node/esm .\index.ts

tsconfig.json

{
"compilerOptions": {
/* Visit https://aka.ms/tsconfig.json to read more about this file */

/* Projects */
// "incremental": true,                              /* Enable incremental compilation */
// "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
// "tsBuildInfoFile": "./",                          /* Specify the folder for .tsbuildinfo incremental compilation files. */
// "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects */
// "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
// "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */

/* Language and Environment */
"target": "es5",                                     /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */
// "lib": [],                                        /* Specify a set of bundled library declaration files that describe the target runtime environment. */
// "jsx": "preserve",                                /* Specify what JSX code is generated. */
// "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
// "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
// "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
// "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
// "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
// "reactNamespace": "",                             /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
// "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
// "useDefineForClassFields": true,                  /* Emit ECMAScript-standard-compliant class fields. */

/* Modules */
"module": "ESNEXT",  // ****HERE                          /* Specify what module code is generated. */
// "rootDir": "./",                                  /* Specify the root folder within your source files. */
"moduleResolution": "node",   // ****HERE                     /* Specify how TypeScript looks up a file from a given module specifier. */
// "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
// "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
// "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
// "typeRoots": [],                                  /* Specify multiple folders that act like `./node_modules/@types`. */
// "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
// "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
// "resolveJsonModule": true,                        /* Enable importing .json files */
// "noResolve": true,                                /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */

/* JavaScript Support */
// "allowJs": true,                                  /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */
// "checkJs": true,                                  /* Enable error reporting in type-checked JavaScript files. */
// "maxNodeModuleJsDepth": 1,                        /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */

/* Emit */
// "declaration": true,                              /* Generate .d.ts files from TypeScript and JavaScript files in your project. */
// "declarationMap": true,                           /* Create sourcemaps for d.ts files. */
// "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
// "sourceMap": true,                                /* Create source map files for emitted JavaScript files. */
// "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
// "outDir": "./",                                   /* Specify an output folder for all emitted files. */
// "removeComments": true,                           /* Disable emitting comments. */
// "noEmit": true,                                   /* Disable emitting files from a compilation. */
// "importHelpers": true,                            /* Allow importing helper functions from tslib once per project, instead of including them per-file. */
// "importsNotUsedAsValues": "remove",               /* Specify emit/checking behavior for imports that are only used for types */
// "downlevelIteration": true,                       /* Emit more compliant, but verbose and less performant JavaScript for iteration. */
// "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
// "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
// "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
// "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
// "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
// "newLine": "crlf",                                /* Set the newline character for emitting files. */
// "stripInternal": true,                            /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
// "noEmitHelpers": true,                            /* Disable generating custom helper functions like `__extends` in compiled output. */
// "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
// "preserveConstEnums": true,                       /* Disable erasing `const enum` declarations in generated code. */
// "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */

/* Interop Constraints */
// "isolatedModules": true,                          /* Ensure that each file can be safely transpiled without relying on other imports. */
// "allowSyntheticDefaultImports": true,             /* Allow 'import x from y' when a module doesn't have a default export. */
"esModuleInterop": true,                             /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */
// "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
"forceConsistentCasingInFileNames": true,            /* Ensure that casing is correct in imports. */

/* Type Checking */
"strict": true,                                      /* Enable all strict type-checking options. */
// "noImplicitAny": true,                            /* Enable error reporting for expressions and declarations with an implied `any` type.. */
// "strictNullChecks": true,                         /* When type checking, take into account `null` and `undefined`. */
// "strictFunctionTypes": true,                      /* When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
// "strictBindCallApply": true,                      /* Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */
// "strictPropertyInitialization": true,             /* Check for class properties that are declared but not set in the constructor. */
// "noImplicitThis": true,                           /* Enable error reporting when `this` is given the type `any`. */
// "useUnknownInCatchVariables": true,               /* Type catch clause variables as 'unknown' instead of 'any'. */
// "alwaysStrict": true,                             /* Ensure 'use strict' is always emitted. */
// "noUnusedLocals": true,                           /* Enable error reporting when a local variables aren't read. */
// "noUnusedParameters": true,                       /* Raise an error when a function parameter isn't read */
// "exactOptionalPropertyTypes": true,               /* Interpret optional property types as written, rather than adding 'undefined'. */
// "noImplicitReturns": true,                        /* Enable error reporting for codepaths that do not explicitly return in a function. */
// "noFallthroughCasesInSwitch": true,               /* Enable error reporting for fallthrough cases in switch statements. */
// "noUncheckedIndexedAccess": true,                 /* Include 'undefined' in index signature results */
// "noImplicitOverride": true,                       /* Ensure overriding members in derived classes are marked with an override modifier. */
// "noPropertyAccessFromIndexSignature": true,       /* Enforces using indexed accessors for keys declared using an indexed type */
// "allowUnusedLabels": true,                        /* Disable error reporting for unused labels. */
// "allowUnreachableCode": true,                     /* Disable error reporting for unreachable code. */

/* Completeness */
// "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. */
"skipLibCheck": true                                 /* Skip type checking all .d.ts files. */
}}

package.json

{
"name": "async-with-ts",
"version": "1.0.0",
"main": "index.js",
"license": "MIT",
"type": "module", // ****HERE
"devDependencies": {
"@types/node-fetch": "^3.0.3",
"ts-node": "^10.2.1",
"typescript": "^4.4.2"
},
"dependencies": {
"node-fetch": "^3.0.0"
  }
}

You should be aware of using this command

node --loader ts-node/esm .\index.ts
5
  • Please provide additional details in your answer. As it's currently written, it's hard to understand your solution.
    – Community Bot
    Commented Sep 4, 2021 at 17:02
  • The above was a canned comment from the review of your answer - Community is a bot, you cannot reply to it. That said, the information and explanations should be added into the answer, not in the comments. Thanks. Commented Sep 6, 2021 at 18:30
  • 1
    OK.I FIXED THE POST Commented Sep 13, 2021 at 6:57
  • 2
    It's recommeded to read the reference from ts-node: github.com/TypeStrong/ts-node/issues/1007
    – silencej
    Commented Nov 12, 2021 at 2:19
  • Point 3. lead to "The file is in the program because: Part of 'files' list in tsconfig.json" Commented May 6, 2022 at 8:12
12

After some experimentation with my ts-node/puppeteer configuration I came up with this:

package.json

{
    "type": "module",
    "scripts": {
        "start": "npx ts-node main.ts"
    },
    ...
}

tsconfig.json

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

Works great for running puppeteer in a TypeScript environment.
(Running NodeJS 19.0.0 with TypeScript 4.9.4 and ts-node 10.9.1)

1
  • 12
    2023 May, on Node.js 20, it does not work.
    – zzzgoo
    Commented May 8, 2023 at 17:38
8

I tried to remove this error by following methods but FAILED :

  1. Using .mts extension.
  2. Using type:commonjs instead of type:module in package.json (this will not let you use 'import' in your TS file, However i wanted that, therefore i consider this try to be failed).
  3. Restarting the VS-Code

Then I tried the following and SUCCEEDED (one of them is enough):

  1. Using --esm flag with ts-node command. e.g => npx ts-node --esm ./src/index.ts
  2. Inside tsConfig.json, add another option after Compiler options' closing bracket named "ts-node" and set its "esm" option to "true", same as below :
{
  "compilerOptions": {
    "module": "ESNext",
    "moduleResolution": "Node",
    /* ... other props ... */
  },
  "ts-node": {
    "esm": true, /* ... Line to be added ... */
  } 
}
2
  • 1
    This is what worked for me. I like the suggestion of modifying tsconfig so you don't have to remember to type --esm on command line
    – gimp3695
    Commented Jan 5 at 21:00
  • 1
    This is same setup that worked for me github.com/TypeStrong/ts-node/issues/… Commented Apr 23 at 12:06
6

You can use ts-node-esm instead of ts-node, keeping "type":"module" in package.json, and using import './module.js' in your .ts files.

Related: https://github.com/TypeStrong/ts-node/issues/1007

UPDATE:

This answer has an even better solution as allows to import modules without .js extension:

https://stackoverflow.com/a/65163089/1482990

1
  • 1
    Yes, we're just trying to run ts-node with modules, thanks! Commented Apr 24, 2022 at 5:28
6

This bug is rather amusing. I found that it is specific to Node.js version 18. To resolve it, I downgraded to Node.js version 16 using NVM. Surprisingly, the issue disappeared without requiring any modifications to my code or configuration. For those utilizing ts-node and nodemon in their development environment, I recommend downgrading to Node.js version 16 instead of using version 18.

4
  • 1
    The problem seems to be specifically with Node 18.19.0. Node versions prior to that should continue to work, so rolling back to 18.18.2 might be the best option rather than going all the way down to 16. I suspect the problem was introduced in: nodejs.org/en/blog/release/… Commented Dec 5, 2023 at 19:19
  • I totally agree on that
    – mitch1009
    Commented Dec 17, 2023 at 10:04
  • I have version 20.5.1 and still the same bug
    – Foreen
    Commented Dec 18, 2023 at 18:57
  • This is a feature of stupid typescript and node having weird format and standard Commented Dec 31, 2023 at 20:10
5

Running ts-node with --esm worked for me.

For example:

ts-node --esm src/App.ts

That error is caused by trying to import modules, which without the ES Modules flag, ts-node doesn't support.

2

I followed advice given herein. I also had to uninstall lodash-es and install lodash instead to make it work.

1

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",
1
  • It solved the issue for me without having to remove "type": "module" or simply avoiding the use of nodemon. Can you please explain what are the paramenters passed in these 2 commands? Commented Sep 3, 2023 at 13:16
1

Some packages needs ES Modules. In my case I was using @Auth/core library which was internally using ES modules instead of CommonJS. So, to resolve this error. I follwed these steps.

Step#1

Upgraded Node to v19 or greater. (In my case node18 was causing error. So, I upgraded to node19)

NODE --> v19.9.0
NPM -->  v9.6.3

Step#2

In package.json add "type"= "module" e.g

{
  ...
  "author": "",
  "type": "module",    <--- * Add this
  "license": "ISC",
  ...
}

Step#3

In tsconfig.json file add ts-node property. e.g

{
  "compileOnSave": true,
  "compilerOptions": {
    ...
    "target": "ESNext",
    "lib": ["ESNext", "esnext.asynciterable"],
    "emitDecoratorMetadata": true,
    "moduleResolution": "node",
    "module": "ESNext",
    ...
  },
  "ts-node": {
    // 
    "esm": true,  <--- Tell ts-node CLI to install the --loader automatically
  },
  "include": ["src/**/*.ts", "src/**/*.json", ".env"],
  "exclude": ["node_modules", "src/http", "src/logs"]
}

Step#4 Update All imports (Or you can try to solve it in a better way)

Import files with exact path and extension(e.g file_name.ts). e.g

import { UserController } from '../controllers/user.controller.ts';

.

Note:- I was getting error with nodemon for development. For that my exec command was

"exec": "ts-node -r tsconfig-paths/register --transpile-only src/server.ts"
2
  • 1
    Thanks for this answer. I also want to add that I use node --loader ts-node/esm src/server.ts instead of ts-node Commented Dec 31, 2023 at 20:10
  • No need to use ts-node/esm in command if using "esm": true, property inside tsconfig.json file Commented Dec 31, 2023 at 21:25
1

Upgrading from [email protected] to [email protected] generated this error when running tests using mocha:

npx mocha -r ts-node/register --reporter list --recursive src/test/**.

Fix (currently) is to rollback to [email protected].

0

July 2022, with the use of ts-node

Node 16.14.2, ts-node 10.8.2

First install ts-node and base configuration

npm install ts-node --save-dev
npm install @tsconfig/node16 --save-dev

tsconfig.json:

{
    "extends": "@tsconfig/node16/tsconfig.json",
    "compilerOptions": {
        "resolveJsonModule": true
    },
    "include": [
        "main.ts"
        // here you can include another directories with sources
    ],
    "exclude": [
        "node_modules"
    ]
}

You can remove everything related to modules/compilation from package.json.

And then you can run your program as

ts-node ./main.ts
0
0

For me (node version 14), for some reason, the problem was that I install the serialize-error package and when I tried to import it to threw that error. To solve it I downgraded the version of the package from 11.0.0 to 8.0.0.

0

If you use PowerShell on VS Code on Windows 11 try to use this command:

ts-node-esm.cmd .\my_script.ts

after this solution: https://stackoverflow.com/a/62099904/8967481

1
  • Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.
    – Community Bot
    Commented Oct 11, 2022 at 11:51
0

For anyone who is running into this issue while trying run an script in an NX project.

# For apps
ts-node --project tsconfig.app.json $yourFilePath

# For libraries
ts-node --project tsconfig.lib.json $yourFilePath

# For tests
ts-node --project tsconfig.spec.json $yourFilePath
0

@vadimk7 wasn't far off, my solution was to change my file extension to .mts and then use ts-node-esm myfile.mts

1
0

After trying all the solutions here, it still didn't work. Then I changed my run script from npx ts-node --esm index.ts to ts-node --project tsconfig.json index.ts and it worked!

0

Try a different version of node. It works okay for version 19 on my machine, but not on 21.


There is an incompatibility between es modules and some versions of node. See the related Github issue

0

The following worked for me :

node --loader ts-node/esm file.ts
-3

before this:

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

I had to update ssri

npm update ssri --depth 5

-3

Not sure if this will help anyone but I fixed it by putting this at the start:

#!/usr/bin/env node
0
-3

Add this to tsconfig.json

{
  /* ... your props ... */

  "ts-node": {
    "compilerOptions": {
      "module": "CommonJS"
    }
  }
}
-4

I wanted to use ES modules instead of commonjs in my project. In addition to making some changes covered in other answers, the last need step for me was to add this to my compilerOptions in tsconfig.json:

"sourceMap": true,

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