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Fix commonjs-extension-resolution-loader #10

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Merged
merged 2 commits into from
Sep 25, 2022
Merged

Fix commonjs-extension-resolution-loader #10

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35765c7
Cleanup existing code
GeoffreyBooth Sep 18, 2022
d17c0ea
Get commonjs-extension-resolution-loader working
GeoffreyBooth Sep 25, 2022
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39 changes: 23 additions & 16 deletions commonjs-extension-resolution-loader/loader.js
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Original file line number Diff line number Diff line change
@@ -1,27 +1,34 @@
import { existsSync } from 'fs';
import { createRequire } from 'module';
import { builtinModules } from 'node:module';
import { dirname } from 'path';
import { URL, fileURLToPath, pathToFileURL } from 'url';
import { cwd } from 'process';
import { fileURLToPath, pathToFileURL } from 'url';
import { promisify } from 'util';

const require = createRequire(import.meta.url);
const baseURL = pathToFileURL(process.cwd() + '/').href;
import resolveCallback from 'resolve/async.js';

export function resolve(specifier, context, defaultResolve) {
const resolveAsync = promisify(resolveCallback);

const baseURL = pathToFileURL(cwd() + '/').href;


export async function resolve(specifier, context, next) {
const { parentURL = baseURL } = context;

// `require.resolve` works with paths, not URLs, so convert to and from
if (specifier.startsWith('node:') || builtinModules.includes(specifier)) {
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nit: I think there's module.isBuiltin now

return next(specifier, context);
}

// `resolveAsync` works with paths, not URLs
if (specifier.startsWith('file://')) {
specifier = fileURLToPath(specifier);
}
const basePath = dirname(fileURLToPath(parentURL));
const resolvedPath = require.resolve(specifier, {paths: [basePath]});
const parentPath = fileURLToPath(parentURL);

if (existsSync(resolvedPath)) {
return {
url: pathToFileURL(resolvedPath).href
};
}
const resolution = await resolveAsync(specifier, {
basedir: dirname(parentPath),
extensions: ['.js', '.json', '.node'],
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I wonder if loaders should be able to expose their own hooks, for example to accept new extensions ... without that, a TS loader would have to implement the same thing but with a different extension, which would require to perform the same filesystem checks multiple times 🤔

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So ambient loaders weren’t enough, now we need loaders for our loaders . . .

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@GeoffreyBooth GeoffreyBooth Sep 25, 2022 •
edited
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accept new extensions

I think the way to achieve this is for loaders to optionally load config files. There’s nothing stopping me from adding some code to the top of loader.js to look for a possibly existing config file, and if found to import it, and read the extensions list from there.

One loader could communicate with the following ones by attaching something to globalThis, I think, since that should be shared within the loaders thread (?). So that’s another way to define/share configuration.

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This is the sort of problem that I'm referring to when I say that the "helper functions" need to compose like hooks.

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Yes, they'll share globalThis (as long as we keep ambient loaders and lay loaders in the same thread).

But context may be a better vehicle, and will is guaranteed to work regardless of threading.

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Yeah, the blocker right now for the helper functions is the API design. I took a stab at it in nodejs/loaders#94 but I feel like that pass leaves a lot to be desired. A similar example is in https://github.com/browserify/resolve#resolveid-opts-cb: see the functions it accepts in the options to override its own lower-level operations.

});
const url = pathToFileURL(resolution).href;

// Let Node.js handle all other specifiers, such as package names
return defaultResolve(specifier, context, defaultResolve);
return next(url, context);
}
118 changes: 118 additions & 0 deletions commonjs-extension-resolution-loader/package-lock.json
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7 changes: 5 additions & 2 deletions commonjs-extension-resolution-loader/package.json
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,9 @@
"start": "npm test",
"test": "node test.js"
},
"author": "Geoffrey Booth <[email protected]>",
"license": "MIT"
"author": "Geoffrey Booth <[email protected]>",
"license": "MIT",
"dependencies": {
"resolve": "^1.22.1"
}
}
16 changes: 8 additions & 8 deletions commonjs-extension-resolution-loader/test.js
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Original file line number Diff line number Diff line change
@@ -1,25 +1,25 @@
import { ok } from 'assert';
import { match } from 'assert';
import { spawn } from 'child_process';
import { execPath } from 'process';


// Run this test yourself with debugging mode via:
// node --inspect-brk --experimental-loader ./loader.js ./fixtures/index.js
// node --inspect-brk --loader ./loader.js ./fixtures/index.js

const child = spawn(execPath, [
'--experimental-loader',
'--loader',
'./loader.js',
'./fixtures/index.js'
]);

let stdout = '';
child.stdout.setEncoding('utf8');
child.stdout.on('data', (data) => {
child.stdout.on('data', data => {
stdout += data;
});

child.on('close', (code, signal) => {
stdout = stdout.toString();
ok(stdout.includes('hello from file.js'));
ok(stdout.includes('hello from folder/index.js'));
child.on('close', (_code, _signal) => {
stdout = stdout.toString();
match(stdout, /hello from file\.js/);
match(stdout, /hello from folder\/index\.js/);
});