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module: fix legacy node specifier resolution to resolve "main" field
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PR-URL: nodejs#38979
Fixes: nodejs#32103
Fixes: nodejs#38739
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>
Reviewed-By: Guy Bedford <guybedford@gmail.com>
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aduh95 authored and foxxyz committed Oct 18, 2021
1 parent 3cba62c commit 8df2479
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Showing 4 changed files with 27 additions and 6 deletions.
26 changes: 20 additions & 6 deletions lib/internal/modules/esm/resolve.js
Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,7 @@ const { getOptionValue } = require('internal/options');
const policy = getOptionValue('--experimental-policy') ?
require('internal/process/policy') :
null;
const { sep, relative } = require('path');
const { sep, relative, resolve } = require('path');
const preserveSymlinks = getOptionValue('--preserve-symlinks');
const preserveSymlinksMain = getOptionValue('--preserve-symlinks-main');
const typeFlag = getOptionValue('--input-type');
Expand Down Expand Up @@ -160,16 +160,18 @@ function getPackageScopeConfig(resolved) {
return packageConfig;
}

/*
/**
* Legacy CommonJS main resolution:
* 1. let M = pkg_url + (json main field)
* 2. TRY(M, M.js, M.json, M.node)
* 3. TRY(M/index.js, M/index.json, M/index.node)
* 4. TRY(pkg_url/index.js, pkg_url/index.json, pkg_url/index.node)
* 5. NOT_FOUND
* @param {string | URL} url
* @returns {boolean}
*/
function fileExists(url) {
return tryStatSync(fileURLToPath(url)).isFile();
return statSync(url, { throwIfNoEntry: false })?.isFile() ?? false;
}

function legacyMainResolve(packageJSONUrl, packageConfig, base) {
Expand Down Expand Up @@ -236,7 +238,19 @@ function resolveExtensions(search) {
return undefined;
}

function resolveIndex(search) {
function resolveDirectoryEntry(search) {
const dirPath = fileURLToPath(search);
const pkgJsonPath = resolve(dirPath, 'package.json');
if (fileExists(pkgJsonPath)) {
const pkgJson = packageJsonReader.read(pkgJsonPath);
if (pkgJson.containsKeys) {
const { main } = JSONParse(pkgJson.string);
if (main != null) {
const mainUrl = pathToFileURL(resolve(dirPath, main));
return resolveExtensionsWithTryExactName(mainUrl);
}
}
}
return resolveExtensions(new URL('index', search));
}

Expand All @@ -252,10 +266,10 @@ function finalizeResolution(resolved, base) {
let file = resolveExtensionsWithTryExactName(resolved);
if (file !== undefined) return file;
if (!StringPrototypeEndsWith(path, '/')) {
file = resolveIndex(new URL(`${resolved}/`));
file = resolveDirectoryEntry(new URL(`${resolved}/`));
if (file !== undefined) return file;
} else {
return resolveIndex(resolved) || resolved;
return resolveDirectoryEntry(resolved) || resolved;
}
throw new ERR_MODULE_NOT_FOUND(
resolved.pathname, fileURLToPath(base), 'module');
Expand Down
3 changes: 3 additions & 0 deletions test/es-module/test-esm-specifiers-legacy-flag.mjs
Original file line number Diff line number Diff line change
Expand Up @@ -6,12 +6,15 @@ import assert from 'assert';
import commonjs from '../fixtures/es-module-specifiers/package-type-commonjs';
// esm index.js
import module from '../fixtures/es-module-specifiers/package-type-module';
// Directory entry with main.js
import main from '../fixtures/es-module-specifiers/dir-with-main';
// Notice the trailing slash
import success, { explicit, implicit, implicitModule }
from '../fixtures/es-module-specifiers/';

assert.strictEqual(commonjs, 'commonjs');
assert.strictEqual(module, 'module');
assert.strictEqual(main, 'main');
assert.strictEqual(success, 'success');
assert.strictEqual(explicit, 'esm');
assert.strictEqual(implicit, 'cjs');
Expand Down
1 change: 1 addition & 0 deletions test/fixtures/es-module-specifiers/dir-with-main/main.js
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
module.exports = 'main';
3 changes: 3 additions & 0 deletions test/fixtures/es-module-specifiers/dir-with-main/package.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
{
"main": "./main.js"
}

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