Add mjs support

[jdmarshall]

If we are talking about 4.0 happening soon I think it would be good for this change from #786 to land in it - adding MJS support.

Tricky thing is though that require() on mjs files didn't get backward compatibility until Node 20, and that's a fairly big jump from where we were before.

[jdmarshall]

And now there is a reason this should go into 4.0: requiring an MJS file requires Node 20 or later in order to function.

[risantos]

@jdmarshall could you please update the wiki?

https://github.com/node-config/node-config/wiki/Configuration-Files#commonjs-javascript-module---js-cjs

Please note that loading files as ESM is not yet supported. So .mjs and .js when "type":"module" or --experimental-modules will not work.

https://github.com/node-config/node-config/wiki/Special-features-for-JavaScript-configuration-files

Loading files as ESM is not yet supported. So .mjs or .js when "type":"module" or --experimental-modules will not work.

[nikhilmisra63]

i have updated it 4.0.0 but still throwing this error

throw new Error("Cannot parse config file: '" + fullFilename + "': " + e3);

[markstos]

@nikhilmisra63 You have to have a new enough Node version. Check that your Node version supports .mjs files.

Also, that error could be thrown because your config file can't be parsed because the syntax in the file is wrong. You haven't provided enough information to be certain what the problem is. Can you run node your-file.mjs to be certain your Node can parse it at all and that it is free of syntax errors?

[nikhilmisra63]

@markstos yes i'm on node 22.11 also all of my files in mjs it just the config module is not working. even i tried to create a sample project where i have just created a default.mjs file inside config folder then a index.mjs with two lines of code

[jdmarshall]

What’s the original error? Breakpoint on that line and paste the entire stack trace here.

[nikhilmisra63]

@jdmarshall @markstos
test.zip
here is the sample code.

and this is what i'm getting

/Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:862
throw new Error("Cannot parse config file: '" + fullFilename + "': " + e3);
^

Error: Cannot parse config file: '/Users/nikhil/Sourcecode/node/dadahub/test/config/default.mjs': Error [ERR_REQUIRE_ESM]: require() of ES Module /Users/nikhil/Sourcecode/node/dadahub/test/config/default.mjs not supported.
Instead change the require of /Users/nikhil/Sourcecode/node/dadahub/test/config/default.mjs to a dynamic import() which is available in all CommonJS modules.
at util.parseFile (/Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:862:11)
at /Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:667:28
at Array.forEach ()
at util.loadFileConfigs (/Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:666:16)
at new Config (/Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:115:27)
at Object. (/Users/nikhil/Sourcecode/node/dadahub/test/node_modules/config/lib/config.js:1524:33)
at Module._compile (node:internal/modules/cjs/loader:1546:14)
at Object..js (node:internal/modules/cjs/loader:1689:10)
at Module.load (node:internal/modules/cjs/loader:1318:32)
at Function._load (node:internal/modules/cjs/loader:1128:12)

Node.js v22.11.0

[jdmarshall]

You've got something else going on and rather than play twenty questions it'd be good if you started with a single, empty mjs file and built up one set of data at a time until you can narrow down the problem with it.

I'm seeing no issues with a simple default.mjs file when I import or require config$4.0.0

$ npm ls config
repro@ /Users/jdmarshall/Projects/cobbler/repro
└── [email protected]
$ cat config/*

$ cat config/*
export default {
    blah: 3
};

$ cat index.mjs
import config from  "config";

console.log(JSON.stringify(config));

$ npm ./index.mjs
{"blah":3}

$ node --version
v22.14.0

$ nvm use 20
Now using node v20.19.0 (npm v10.8.2)

$ npm ./index.mjs
{"blah":3}

[nikhilmisra63]

not sure what is real issue but i'm trying to run the same code which i have attached in my last comment and that has only one file and still i'm getting the error.

for now i move to .json instead of .mjs and it is working fine.

[jdmarshall]

I tried your sample file. Unable to reproduce.

node index.mjs
testing config module with mjs

how are you starting? You're leaving out bits of your repro case and I haven't left out any of mine.

[nikhilmisra63]

here is the complete screenshot please let me know if you need anything else?

[jdmarshall]

Anyone else able to repro this case? @markstos @skitscha ?

I’m not sure what else to try here. Other than suggesting trying the same node versions I’m using, which should not matter.

[jdmarshall]

nodejs/node#56927 I think your node versions may be too old.

[nikhilmisra63]

Hey, just found the culprit — it wasn’t working with Node 22.11, but after updating to 22.14, it’s working fine. I should’ve tested with other versions earlier. Really appreciate your efforts on this, @jdmarshall — thanks a lot!

[jdmarshall]

Okay. Looks like I need to update the docs and release notes. I misremembered these as being a launch feature and it seems that’s only in 24.

[jdmarshall]

Done