ES modules not supported

[LinusU]

I'm getting the following error as soon as the compiled app boots:

node:internal/modules/cjs/loader:930
  throw err;
  ^

Error: Cannot find module '/snapshot/dhjaks/index.js'
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:927:15)
    at Function._resolveFilename (pkg/prelude/bootstrap.js:1776:46)
    at Function.Module._load (node:internal/modules/cjs/loader:772:27)
    at Function.runMain (pkg/prelude/bootstrap.js:1804:12)
    at node:internal/main/run_main_module:17:47 {
  code: 'MODULE_NOT_FOUND',
  requireStack: []
}

Here is a minimal reproducible example:

package.json

{ "type": "module" }

index.js

import os from 'os'

console.log(os.arch())

Build command:

pkg index.js

[sartaj-sphp]

You didn't post your complete package.json file. So i think you didn't add your sub folders as scripts. For example if you want to add dhjaks folder as script folder then you need to add this in package file like.
{
"name": "mdm5",
"version": "1.0.1",
"description": "MDM",
"main": "start.js",
"bin": "start.js",
"scripts": {
"start": "node ."
},
"pkg": {
"scripts": [
"dhjaks/*.js"
],
"assets": [],
"targets": [
"node12",
"linux-x64",
"macos-x64",
"win-x64"
]
},
"author": "demo",
"license": "ISC",
"dependencies": {
}
}
assume dhjaks is subfolder under pacakge file parent folder. use build command pkg ./package.json

[LinusU]

@Sartaj-Singh I actually did post my complete package.json file ☺️

The dhjaks folder is the folder of my entire package. My entire package only has two files: package.json & index.js. The goal is for it to just print out one line and then exit.

I did it like this to make a minimal test case that shows the problem.

---

I now tried to use pkg package.json instead:

$ mkdir foobar
$ cd foobar
$ echo '{ "name": "test", "bin": "index.js", "type": "module" }' > package.json
$ echo 'import os from "os"' > index.js
$ echo 'console.log(os.arch())' >> index.js
$ npx pkg package.json
> pkg@5.3.1
> Warning Failed to make bytecode node16-arm64 for file /snapshot/foobar/index.js

$ ./test
node:internal/modules/cjs/loader:930
  throw err;
  ^

Error: Cannot find module '/snapshot/foobar/index.js'
    at Function.Module._resolveFilename (node:internal/modules/cjs/loader:927:15)
    at Function._resolveFilename (pkg/prelude/bootstrap.js:1776:46)
    at Function.Module._load (node:internal/modules/cjs/loader:772:27)
    at Function.runMain (pkg/prelude/bootstrap.js:1804:12)
    at node:internal/main/run_main_module:17:47 {
  code: 'MODULE_NOT_FOUND',
  requireStack: []
}

[sartaj-sphp]

Check this line:- Warning Failed to make bytecode node16-arm64 for file /snapshot/foobar/index.js
don't use npm or npx, pkg can run independently.
Try to set target in pacakge file like:- "targets": [
"node12",
"linux-x64",
"macos-x64",
"win-x64"
]

[LinusU]

don't use npm or npx, pkg can run independently.

npx is just a way to install & run the package without clobbering your global installs. That is not what's causing problems here since I have tried it with a locally installed version of pkg as well.

Try to set target in pacakge file like

Setting the targets doesn't change anything, I've tried different targets and even running on different platforms...

It does however run if I don't use "type": "module", and use require instead of import, so this issue is clearly related to that.

[sartaj-sphp]

I always create const with require. import statement may be not supported by pkg. I think no need type=module if you compile stand alone executable.

[LinusU]

import statement may be not supported by pkg

If it isn't, then this is a feature request

I think no need type=module if you compile stand alone executable.

I need it because I need to import packages which are ESM-only

[webhype]

Hi, could someone clarify clearly on the home page (README.md) whether or not pkg supports ESMs (ES modules) at all? I know it's a free open-source labor-of-love project so I am not demanding anything. It is what it is and it is appreciated as-is. Just would like a clear positioning so we don't need to waste our time trying to package "type": "module" projects, if that's not supported at all. ESMs are not exactly a new invention so a one-liner positioning in the docs would be helpful. If ESM packaging is hopeless with pkg, does anyone know of a workaround (other than rewriting all your code back into CommonJS)? Cheers!

[CleyFaye]

There is the option of using a barebone webpack config to create a single JS file containing all dependencies and not having any external import. Something like this:

const config = {
  mode: "production",
  entry: "./src/main.ts",
  target: "node",
  output: {
    path: resolve(__dirname, "build", "lib"),
    chunkFormat: "commonjs",
  },
};

The output is then usable with pkg.

It should also be possible to update pkg to support ESM; last time I checked I saw two main issues, the babel configuration used (which can be either completely dropped or updated to support module input with a single change), and bytecode generation that failed. Since I already knew of the webpack option I gave up, but fixing bytecode generation with ESM should be doable since node now have full support for it.

[robertsLando]

For anyone interested I suggest you to firstly use ncc to compile your modules and then use pkg to compile them into executable. There is already an open feature request to include ncc in pkg, maybe with an option

[CleyFaye]

That was what we were doing until a recent update of ncc added compatibility with module-based source. It now produce files that pkg can't use; I could restore the build setup to get the actual error message if needed, but it was something along the line of not handling import statement that were indeed found in the output of ncc.

[robertsLando]

added compatibility with module-based source

Cannot this be disabled with an option?

[CleyFaye]

Not with an option, sadly. But in the end, ncc basically wraps webpack, hence our solution above. I'm not sure which of the two tools should change, but as it is some features of pkg are simply not used (bundling packages, detecting __dirname, etc.). Still the main feature works perfectly, so it's not so bad.

[robertsLando]

By double checking the code seems import statements should be supported:

pkg/lib/detector.ts

Line 258 in 59125d1

was = visitorImport(node);

Maybe something isn't working as expected