replace webpack with rolldown in builder

Author: zloirock

.github/workflows/ci.yml

@@ -50,9 +50,8 @@ jobs:
     strategy:
       matrix:
         node:
-          - 20.9
-          - 21
-          - ^22.5.1
+          - ^20.19
+          - ^22.12
           - 23
           - 24
           - 25
@@ -74,9 +73,8 @@ jobs:
           - windows-latest
           - macos-latest
         node:
-          - 20.9
-          - 21
-          - ^22.5.1
+          - ^20.19
+          - ^22.12
           - 23
           - 24
           - 25

.gitignore

@@ -24,6 +24,7 @@ node_modules/
 /packages/core-js/LICENSE
 /packages/core-js-babel-plugin/LICENSE
 /packages/core-js-builder/LICENSE
+/packages/core-js-builder/__tmp__/
 /packages/core-js-bundle/LICENSE
 /packages/core-js-bundle/index.js
 /packages/core-js-bundle/minified.js

package-lock.json

@@ -32,6 +32,6 @@
     "@core-js/compat": "4.0.0-alpha.0"
   },
   "engines": {
-    "node": ">=20.19.0"
+    "node": "^20.19.0 || >=22.12.0"
   }
 }

packages/core-js-babel-plugin/package.json

@@ -1,3 +1,4 @@
 node_modules/
+__tmp__/
 *.log
 .*

packages/core-js-builder/.npmignore

@@ -0,0 +1,10 @@
+const version = '4.0.0-alpha.0';
+
+/* eslint-disable prefer-template -- for better formatting */
+export default '/**\n' +
+               ' * core-js ' + version + '\n' +
+               ' * © 2013–2025 Denis Pushkarev (zloirock.ru), 2025–2026 CoreJS Company (core-js.io). All rights reserved.\n' +
+               ' * license: https://github.com/zloirock/core-js/blob/v' + version + '/LICENSE\n' +
+               ' * source: https://github.com/zloirock/core-js\n' +
+               ' */';
+/* eslint-enable prefer-template -- for better formatting */

packages/core-js-builder/config.js

@@ -1,12 +1,11 @@
-'use strict';
 /* eslint-disable no-console -- output */
-const { promisify } = require('node:util');
-const { mkdir, readFile, unlink, writeFile } = require('node:fs/promises');
-const { dirname, join } = require('node:path');
-const tmpdir = require('node:os').tmpdir();
-const webpack = promisify(require('webpack'));
-const compat = require('@core-js/compat/compat');
-const { banner } = require('./config');
+import { mkdir, readFile, rm, writeFile } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { build } from 'rolldown';
+import { transform } from '@swc/core';
+import compat from '@core-js/compat/compat.js';
+import banner from './config.mjs';
 
 function normalizeSummary(unit = {}) {
   let size, modules;
@@ -18,7 +17,19 @@ function normalizeSummary(unit = {}) {
   } return { size, modules };
 }
 
-module.exports = async function ({
+function importIt(it) {
+  return `import 'core-js/modules/${ it }.js';\n`;
+}
+
+function requireIt(it) {
+  return `require('core-js/modules/${ it }');\n`;
+}
+
+function importModules(modules, format = 'esm') {
+  return modules.map(format === 'esm' ? importIt : requireIt).join('');
+}
+
+export default async function ({
   modules = null,
   exclude = [],
   targets = null,
@@ -37,33 +48,46 @@ module.exports = async function ({
 
   if (list.length) {
     if (format === 'bundle') {
-      const tempFileName = `core-js-${ Math.random().toString(36).slice(2) }.js`;
-      const tempFile = join(tmpdir, tempFileName);
-
-      await webpack({
-        mode: 'none',
-        node: false,
-        target: ['es5', 'node'],
-        entry: list.map(it => require.resolve(`core-js/modules/${ it }`)),
-        output: {
-          filename: tempFileName,
-          path: tmpdir,
-        },
-      });
+      const tempDir = join(dirname(fileURLToPath(import.meta.url)), '__tmp__');
+      const tempFile = join(tempDir, `core-js-${ Math.random().toString(36).slice(2) }.js`);
+      const templateFile = `${ tempFile }-template.js`;
+
+      try {
+        await mkdir(tempDir, { recursive: true });
+        await writeFile(templateFile, importModules(list));
 
-      const file = await readFile(tempFile);
+        await build({
+          input: templateFile,
+          platform: 'neutral',
+          treeshake: false,
+          output: {
+            externalLiveBindings: false,
+            format: 'iife',
+            file: tempFile,
+            keepNames: true,
+            minifyInternalExports: true,
+          },
+        });
 
-      await unlink(tempFile);
+        code = String(await readFile(tempFile, 'utf8'));
+      } finally {
+        await rm(templateFile, { force: true });
+        await rm(tempFile, { force: true });
+      }
 
-      code = `!function (undefined) { 'use strict'; ${
-        // compress `__webpack_require__` with `keep_fnames` option
-        String(file).replace(/function __webpack_require__/, 'var __webpack_require__ = function ')
-      } }();\n`;
+      // rolldown helpers / wrappers contain arrows
+      code = (await transform(code, {
+        env: {
+          include: [
+            'transform-arrow-functions',
+            'transform-shorthand-properties',
+          ],
+        },
+      })).code;
+
+      code = `!function (undefined) { 'use strict'; ${ code } }();\n`;
     } else {
-      const template = it => format === 'esm'
-        ? `import 'core-js/modules/${ it }.js';\n`
-        : `require('core-js/modules/${ it }');\n`;
-      code = list.map(template).join('');
+      code = importModules(list, format);
     }
   }
 
@@ -90,4 +114,4 @@ module.exports = async function ({
   }
 
   return { script };
-};
+}

packages/core-js-builder/config.mjs

@@ -4,7 +4,7 @@
   "publishConfig": {
     "access": "public"
   },
-  "type": "commonjs",
+  "type": "module",
   "description": "core-js builder",
   "repository": {
     "type": "git",
@@ -26,14 +26,26 @@
     "url": "http://zloirock.ru"
   },
   "sideEffects": false,
-  "main": "index.js",
+  "main": "index.mjs",
+  "exports": {
+    ".": {
+      "types": "./index.d.ts",
+      "default": "./index.mjs"
+    },
+    "./index.mjs": {
+      "types": "./index.d.ts",
+      "default": "./index.mjs"
+    },
+    "./config.mjs": "./config.mjs"
+  },
   "types": "index.d.ts",
   "dependencies": {
-    "core-js": "4.0.0-alpha.0",
     "@core-js/compat": "4.0.0-alpha.0",
-    "webpack": "^5.104.1"
+    "@swc/core": "^1.15.11",
+    "core-js": "4.0.0-alpha.0",
+    "rolldown": "^1.0.0-rc.2"
   },
   "engines": {
-    "node": ">=20.19.0"
+    "node": "^20.19.0 || >=22.12.0"
   }
 }

packages/core-js-builder/index.js packages/core-js-builder/index.mjspackages/core-js-builder/index.js renamed to packages/core-js-builder/index.mjs

@@ -1,6 +1,6 @@
 import { minify } from 'terser';
 import builder from '@core-js/builder';
-import config from '@core-js/builder/config.js';
+import config from '@core-js/builder/config.mjs';
 
 const { cyan, green } = chalk;
 const ESMODULES = argv._.includes('esmodules');