NextJS: Run a Typescript script on the server

Question

I have a NextJS/Typescript project where I want to add a CLI script which should process some files on the server.

Unfortunately I don't manage to run the script.

Example script src/cli.ts:

console.log("Hello world");
// Process files

I tried to run the script with:

ts-node src/cli.ts

But I get this error message:

src/cli.ts:1:1 - error TS1208: 'cli.ts' cannot be compiled under '--isolatedModules' because it is considered a global script file. Add an import, export, or an empty 'export {}' statement to make it a module.

When I add an empty 'export {}' statement I get this error message:

(node:15923) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.

As far as I know it is now not possible to use NextJS with ES modules.

Is there another way to run the script in a NextJS project? Maybe I need to change the webpack config?

I'm using the latest versions: Next 11, Typescript 4.3, Node 14.18, ts-node 10.13 with the default tsconfig.json, package.json.

philippe_b · Accepted Answer · 2022-12-03 17:51:39Z

25

You can use TSX, which plays nicely with NextJS, for both JavaScript and TypeScript. No need for extra configuration or anything.

Install it:

yarn add -D tsx

Declare your script in package.json:

...
"scripts": {
  ...
  "my-cli-script": "tsx src/cli.ts"
},

Run it:

yarn my-cli-script

answered Dec 3, 2022 at 17:51

philippe_b

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5 Comments

Marek Lisý Over a year ago

I was literally going insane. Tried about 20 different solutions, until this worked. Thank you!!!

philippe_b Over a year ago

@MarekLisý Same here :)

mettjus Over a year ago

Thanks! This worked for me. If you want you can also just npx tsx path/to/your/script.ts, without the need to add tsx to the dependencies and an appropriate script in package.json.

Eric Over a year ago

I tried a LOT of different things to get my .ts script (used for some db updates) to execute with ts-node and nothing worked. tsx worked on first try, no changes to tsconfig.json or package.json. Incredible. Thanks!

jacktim Over a year ago

TSX is the answer - not sure why ts-node is even suggested in places

brc-dd · Accepted Answer · 2021-11-08 06:18:14Z

Run this instead:

npx ts-node --skip-project src/cli.ts

Reference: https://github.com/TypeStrong/ts-node#tsconfig

The --skip-project flag will not resolve/load your tsconfig.json and, thus, ignore the "isolatedModules": true required by Next.js.

You can also create a separate tsconfig file for ts-node and use the --project [path] option.

Another way is to override configuration for ts-node in your tsconfig.json itself like this:

{
  "extends": "ts-node/next/tsconfig.json",

  "ts-node": {
    "compilerOptions": {
      // compilerOptions specified here will override those declared below,
      // but *only* in ts-node.  Useful if you want ts-node and tsc to use
      // different options with a single tsconfig.json.

      "isolatedModules": false
    }
  },

  "compilerOptions": {
    // typescript options here
  }
}

Reference: https://github.com/TypeStrong/ts-node#via-tsconfigjson-recommended

Luke · Accepted Answer · 2023-03-12 17:54:11Z

3

Following on from @brc-dd answer.

The --skip-project flag is now --skipProject

And for the new TSConfig to specify when running the script you would need the following:

{
  "extends": "ts-node/next/tsconfig.json",

  "ts-node": {
    "compilerOptions": {
      // compilerOptions specified here will override those declared below,
      // but *only* in ts-node.  Useful if you want ts-node and tsc to use
      // different options with a single tsconfig.json.

      "module": "CommonJS",
      "isolatedModules": false
    }
  },

  "compilerOptions": {
    // typescript options here
  }
}

All I added to this was: "module": "CommonJS",

answered Mar 12, 2023 at 17:54

Luke

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