Support .js config files in "type": "module" projects?

[michael42]

Hi there,

would you consider supporting .js files inside projects with "type": "module" set? Otherwise is pretty hard to provide config files sometimes, because not every user of lilconfig actually includes .cjs as an allowed file extension.

Currently I'm using the following patch, which should work for CommonJS and ECMAScript Modules since Node 12, so it would require a semver-major bump (or a fallback for Node 10):

diff --git a/dist/index.js b/dist/index.js
index a153607e305eb6d40b735aa176eee388b8172dc9..497efc7dc60165b306f46211fb7ddd811b51ef72 100644
--- a/dist/index.js
+++ b/dist/index.js
@@ -28,7 +28,7 @@ function getSearchPaths(startDir, stopDir) {
     }, { searchPlaces: [], passedStopDir: false }).searchPlaces;
 }
 exports.defaultLoaders = Object.freeze({
-    '.js': require,
+    '.js': id => import(id).then(mod => mod.default),
     '.json': require,
     '.cjs': require,
     noExt(_, content) {
@@ -123,7 +123,7 @@ function lilconfig(name, options) {
                 }
                 else {
                     validateLoader(loader, loaderKey);
-                    result.config = loader(filepath, content);
+                    result.config = await loader(filepath, content);
                 }
                 result.filepath = filepath;
                 break;

[antonk52]

Hi and thank you for the issue.

Since this package attempts to mimic cosmiconfig, I would rather to wait for them to make a major release with support for ESM native node modules and drop nodejs v10. From my understanding it is not yet implemented as nodejs does not offer an API to clear cache for imported modules like require.cache which is a blocker for cosmiconfig.

From your diff I can see that there is currently an issue with lilconfig as loaders can be async for lilconfig function. You can submit a PR to add the two missing awaits and I am happy to merge it and publish a new version that would allow you to provide an ESM loader instead of patching a dependency, ie

const loadESMDefault = p => import(p).then(x => x.default)

lilconfig('myapp', {
  loaders: {
    '.js': loadESMDefault,
    '.mjs': loadESMDefault,
  }
}).load('./path/to/esm/file.js') // Promise<config>

Await is missing here and here.

Let me know what you think about this.

[michael42]

Thanks for the fast response and great idea splitting the patch. I created a pull request adding the awaits (and learned a bit about the API while writing a test for it).

[antonk52]

Nicely done. I've released a new version v2.0.5 with your fix, this should make it easier for people to consume ESM configs.

[marekdedic]

Hi, it seems to me that osmiconfig now supports this looking at the changelog for version 8.2.0. Could we please reopen this? Happy to send a PR if necessary...

[antonk52]

Hi @marekdedic this sounds reasonable to me. Happy to review and merge your PR. I’ve reopened the issue.

[antonk52]

closed by #46