json-6 require not working?

[JakobJingleheimer]

Sorry, I'm not sure exactly what the problem is, but it appears json-6/lib/require doesn't work (and I'm seeing that require.extensions is deprecated).

When I try to import a .json6 file and run it with mochajs/mocha (which I think uses standard-things/esm), I get the following error:

TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".json6"
for …/dummy-data.json6
    at new NodeError (node:internal/errors:259:15)
    at Loader.defaultGetFormat [as _getFormat] (node:internal/modules/esm/get_format:65:15)
    at Loader.getFormat (node:internal/modules/esm/loader:101:42)
    at Loader.getModuleJob (node:internal/modules/esm/loader:230:31)
    at async ModuleWrap.<anonymous> (node:internal/modules/esm/module_job:53:21)
    at async Promise.all (index 0)
    at async link (node:internal/modules/esm/module_job:58:9)

I've included json-6/lib/require in mocha's --require and confirmed the file is executed; however, the function set for '.json6' never executes.

I see that there is specific mention of JSON6 in esm's readme, so I tried adding the cited config to my package.json, but to no effect:

"esm": {
  "JSON6": true
}

[d3x0r]

Okay.

I updated my one-shot test batch file to do this..

mocha --require chai/register-expect --require ../lib/require.js %*

I added tests test/1.09-require.js and test/1.09-require.mjs ; the first works without issue.
the second works when I manually run tests using the above command
the second fails with Unknown file extension error mentioned above, when run through npm...

but it works okay from the command line.

M:\javascript\JSON6\test>mocha --require chai/register-expect --require ../lib/require.js 1.0.9-require.mjs


  Added in 1.0.9 - require(esm)
    √ allows using require on extension


  1 passing (5ms)

I had to rename test/1.0.9-require.mjs to .fail to allow pushing... I'm not sure how to get it to work from npm... from just mocha it seems to work fine.

https://github.com/d3x0r/JSON6/tree/master/test renaming the require test to .mjs instead of .mjs.fail
then npm run test-lite fails.

> json-6@1.0.8 mocha-lite
> mocha --require chai/register-expect --require ./lib/require.js



  Added in 1.0.9 - require(cjs)
    √ allows using require on extension

  Added in 1.0.9 - require(esm)
    √ allows using require on extension
    1) allows using require on extension


  2 passing (14ms)
3:09 PM  1 failing
1) Added in 1.0.9 - require(esm)
     allows using require on extension:
      Uncaught TypeError [ERR_UNKNOWN_FILE_EXTENSION]: Unknown file extension ".json6" for M:\javascript\JSON6\test\1.0.9-require.json6
    at new NodeError 

[JakobJingleheimer]

Hmm, if you're running it via mocha directly, I presume you've installed mocha globally? That could make a huge difference (and is unlikely to be an uncommon real-world scenario).

I get the same Unknown file extension error via npx mocha btw.

Preliminary results with $> NODE_ENV=test node_modules/mocha/bin/mocha are…promising (though not ideal): at least Mocha is complaining about actual errors now (previously it was erroring out before getting to them).

[d3x0r]

found deprecation
https://nodejs.org/api/all.html#DEP0039

v6.12.0, v4.8.6 | A deprecation code has been assigned.

that was a long time ago... could wish they included 'and has been replaced with....'

[d3x0r]

I'd maybe recommend copying the snippet of code from require.js that loads and parses the file and returns an object.... as a workaround.
I have another project that has a custom import() function that handles it; but I've not found how to hook into the module loader chain of node.

[JakobJingleheimer]

I took a quick gander at @babel/register hoping there was something quick I could glean and incorporate from that, but it's much more involved than I was hoping ☹️

[d3x0r]

This is the module the error is thrown from... specifically the list of extensions internal - with no way to add another list
https://github.com/nodejs/node/blob/master/lib/internal/modules/esm/get_format.js#L17-L22

This has the resolve logic which I think prefilters '.json' ... it looks like it supports file:, data:, and node: URL resolutions for filenames... (not really any help)
https://github.com/nodejs/node/blob/master/lib/internal/modules/esm/resolve.js

[JakobJingleheimer]

I think the way to handle this now is: https://nodejs.org/api/esm.html#esm_hooks

Looking at get_format.js, I found a workaround to avoid the error: get_format.js#L65 add --experimental-specifer-resolution=node

This works the same for me as calling mocha directly (via node_modules/mocha/bin/mocha):

$> npm run test --experimental-specifer-resolution=node

(it also works when appended to the npm script)

[d3x0r]

that doesn't work for me... I didn't see any sign that using the other map would have helped any... that still doesn't relate to 'require.extensions' ?

(you mispelled specifier above :) and for a while node was saying it couldn't take that option)

> SET NODE_OPTIONS=--experimental-specifier-resolution=node && mocha --require chai/register-expect --require ./lib/require.js

node:internal/process/esm_loader:74

    internalBinding('errors').triggerUncaughtException(

                              ^



TypeError [ERR_INVALID_RETURN_PROPERTY_VALUE]: Expected string to be returned for the "format" from the "loader getFormat" function but got type object.

    at new NodeError (node:internal/errors:259:15)

    at Loader.getFormat (node:internal/modules/esm/loader:110:13)

[JakobJingleheimer]

I think it's not working for you because I didn't misspell specifer: it's misspelled in the source code (get_format.js line 65)

      if (experimentalSpeciferResolution === 'node') {

[JakobJingleheimer]

By the way, for the esm require, it looks like a custom transpiler loader is the way to go: https://github.com/nodejs/node/blob/master/doc/api/esm.md#transpiler-loader

That doc explicitly says require.extensions doesn't work for esm / import: https://github.com/nodejs/node/blob/master/doc/api/esm.md#no-requireextensions

[d3x0r]

okay so do I need to do a @rollup/json6-plugin etc ? babel?

[d3x0r]

that doesn't solve everything though - I do still read .jsox(json6) files for configuration files because of human editability... so it should really always be a dynamic sort of thing that wouldn't be included...

[d3x0r]

So I'm about to update the test to be 'success is to throw an error', and update the readme about limitations.

[JakobJingleheimer]

I think neither of those. Basically an esm version of the existing lib/require accomplished via that loader stuff. Then append whatever command with --experimental-loader json-6/lib/es-loader. Ex

// package.json
{
  "scripts": {
    "test": "NODE_ENV=test mocha ./src --experimental-loader json-6/lib/es-loader"
  }
}

[d3x0r]

This should basically work...
https://github.com/d3x0r/JSON6/blob/master/lib/import.mjs
--experimental-loader=./lib/import.mjs

updating the projects own build to include that and require causes it to fail to import 'node_modules/mocha/bin/mocha' because it doesn't have an extension.... but again was able to run the tests as a one-off with the extra flags. and this fails for me

SET NODE_OPTIONS=--experimental-loader=./lib/import.mjs && mocha --require chai/register-expect --require ./lib/require.js

However, the new loader should generally work... it worked as below...

This usage worked.

import {default as config} from './1.0.9-require.json6'
console.log( config );

This method also worked.

return import( "./1.0.9-require.json6" ).then( config=>{
			config.default //...