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hugo/common/hexec/esmloader.mjs
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Bjørn Erik Pedersen ae7bf74b3e common/hexec: Make NODE_PATH a fallback for ESM bare imports
Node's ESM resolver does not consult NODE_PATH (unlike CJS require), so
an ESM postcss.config.js shipped by a Hugo theme fails when loaded from
the module cache: bare imports like `import x from "postcss-import"`
have no node_modules to walk up to.

Install a synchronous resolver hook (module.registerHooks) via
--import=data:... on every Node invocation. On ERR_MODULE_NOT_FOUND for
a bare specifier it resolves the package from each NODE_PATH entry via
createRequire().resolve(). No-op for relative, absolute, URL-scheme and
non-MODULE_NOT_FOUND failures. Synchronous hooks run on the main thread,
so no --allow-worker is needed under the Node permission model.

Fixes #13987

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-13 22:00:04 +02:00

53 lines
1.8 KiB
JavaScript

// Node.js ESM resolver hook installed by Hugo.
//
// Node's ESM resolver does not consult NODE_PATH, unlike CJS require().
// That breaks postcss.config.js / babel.config.js / etc. files written in
// ESM and loaded from outside the project tree (typically the Hugo module
// cache): bare imports like `import x from "postcss-import"` cannot be
// resolved by walking up from the file's location.
//
// This hook makes the ESM resolver fall back to NODE_PATH for bare
// specifiers when Node's normal resolution fails. It is a no-op for
// relative/absolute paths and URL-scheme specifiers, and it never fires
// unless Node would itself have thrown ERR_MODULE_NOT_FOUND.
//
// Uses the synchronous registerHooks API so it runs on the main thread and
// does not require --allow-worker under the Node permission model.
import { registerHooks, createRequire } from 'node:module';
import { pathToFileURL } from 'node:url';
const resolvers = [];
const np = process.env.NODE_PATH;
if (np) {
const sep = process.platform === 'win32' ? ';' : ':';
for (const p of np.split(sep)) {
if (p) resolvers.push(createRequire(p + '/_'));
}
}
function isBareSpecifier(s) {
if (!s) return false;
if (s.startsWith('.') || s.startsWith('/') || s.startsWith('#')) return false;
if (/^[a-z][a-z0-9+.-]*:/i.test(s)) return false;
return true;
}
registerHooks({
resolve(specifier, context, nextResolve) {
try {
return nextResolve(specifier, context);
} catch (err) {
if (err?.code !== 'ERR_MODULE_NOT_FOUND') throw err;
if (!isBareSpecifier(specifier)) throw err;
for (const r of resolvers) {
try {
const resolved = r.resolve(specifier);
return { url: pathToFileURL(resolved).href, shortCircuit: true, format: null };
} catch (_) { /* try next */ }
}
throw err;
}
},
});