Rework @core-js/builder

.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

packages/core-js-babel-plugin/package.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-builder/.npmignore

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

packages/core-js-builder/README.md

@@ -31,6 +31,8 @@ const { script } = await builder({
   // output format, 'bundle' by default, can be 'cjs' or 'esm', and in this case
   // the result will not be bundled and will contain imports of required modules
   format: 'bundle',
+  // minify the output in the case of format: bundle, `true` by default
+  minify: true,
   // optional target filename, if it's missed a file will not be created
   filename: PATH_TO_MY_COREJS_BUNDLE,
 });

packages/core-js-builder/config.mjs

@@ -0,0 +1,59 @@
+const version = '4.0.0-alpha.0';
+
+/* eslint-disable prefer-template -- for better formatting */
+export const banner = '/**\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 */
+
+export function getRolldownOptions(input, output) {
+  return {
+    input,
+    platform: 'neutral',
+    treeshake: false,
+    output: {
+      externalLiveBindings: false,
+      format: 'iife',
+      file: output,
+      keepNames: true,
+      minifyInternalExports: true,
+    },
+  };
+}
+
+export const ModernSyntax = [
+  'arrow-functions',
+  'shorthand-properties',
+];
+
+export const MinifyOptions = {
+  minify: true,
+  jsc: {
+    minify: {
+      compress: {
+        arrows: false,
+        ecma: 5,
+        hoist_funs: true,
+        keep_fnames: true,
+        pure_getters: true,
+        reduce_funcs: true,
+        // document.all detection case
+        typeofs: false,
+        unsafe_proto: true,
+        unsafe_undefined: true,
+      },
+      mangle: {
+        keep_fnames: true,
+        safari10: true,
+        toplevel: true,
+      },
+      format: {
+        comments: false,
+        ecma: 5,
+      },
+    },
+  },
+};

packages/core-js-builder/index.d.ts

@@ -22,6 +22,8 @@ type Options = Pick<CompatOptions, "exclude" | "modules" | "targets"> & {
   format?: Format,
   /** optional target filename, if it's missed a file will not be created */
   filename?: string,
+  /** minify the output in the case of format: bundle, `true` by default */
+  minify?: boolean,
   /** shows summary for the bundle, disabled by default */
   summary?: Summary,
 };

packages/core-js-builder/index.mjs

@@ -0,0 +1,126 @@
+/* eslint-disable no-console -- output */
+import { mkdir, readFile, rm, writeFile } from 'node:fs/promises';
+import { dirname, join } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { styleText } from 'node:util';
+import { build } from 'rolldown';
+import { transform } from '@swc/core';
+import compat from '@core-js/compat/compat.js';
+import { banner, getRolldownOptions, MinifyOptions, ModernSyntax } from './config.mjs';
+
+function normalizeSummary(unit = {}) {
+  let size, modules;
+  if (typeof unit != 'object') {
+    size = modules = !!unit;
+  } else {
+    size = !!unit.size;
+    modules = !!unit.modules;
+  } return { size, modules };
+}
+
+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,
+  format = 'bundle',
+  minify = true,
+  filename = null,
+  summary = {},
+} = {}) {
+  if (!['bundle', 'cjs', 'esm'].includes(format)) throw new TypeError('Incorrect output type');
+
+  summary = { comment: normalizeSummary(summary.comment), console: normalizeSummary(summary.console) };
+
+  const TITLE = filename ?? '`core-js`';
+
+  if (typeof TITLE != 'string') throw new TypeError('Incorrect filename');
+
+  let script = banner;
+  let code = '\n';
+
+  const { list, targets: compatTargets } = compat({ targets, modules, exclude });
+
+  if (list.length) {
+    if (format === 'bundle') {
+      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));
+
+        await build(getRolldownOptions(templateFile, tempFile));
+
+        code = String(await readFile(tempFile, 'utf8'));
+      } finally {
+        await rm(templateFile, { force: true });
+        await rm(tempFile, { force: true });
+      }
+
+      const swcOptions = {};
+
+      // rolldown helpers / wrappers contain es2015 syntax
+      let syntax = ModernSyntax;
+
+      if (targets) {
+        syntax = compat({ targets, modules: syntax, __external: true }).list;
+      }
+
+      const swcTransforms = syntax.map(it => `transform-${ it }`);
+
+      if (swcTransforms.length) Object.assign(swcOptions, {
+        env: {
+          include: swcTransforms,
+        },
+      });
+
+      if (minify) Object.assign(swcOptions, MinifyOptions);
+
+      if (swcTransforms.length || minify) {
+        code = (await transform(code, swcOptions)).code;
+      }
+
+      // swc and rolldown considers output code as a module and drops 'use strict'
+      code = `!function () { 'use strict'; ${ code } }();\n`;
+    } else {
+      code = importModules(list, format);
+    }
+  }
+
+  if (summary.comment.size) script += `/*\n * size: ${ (code.length / 1024).toFixed(2) }KB */`;
+  if (summary.comment.modules) script += `/*\n * modules:\n${ list.map(it => ` * ${ it }\n`).join('') } */`;
+  if (code) script += `\n${ code }`;
+
+  if (summary.console.size) {
+    console.log(styleText('green', `bundling ${ styleText('cyan', TITLE) }, size: ${
+      styleText('cyan', (script.length / 1024).toFixed(2))
+    }KB`));
+  }
+
+  if (summary.console.modules) {
+    console.log(styleText('green', `bundling ${ styleText('cyan', TITLE) }, modules:`));
+    if (list.length) for (const it of list) {
+      console.log(styleText('cyan', `${ it + (targets ? styleText('green', ` for ${ styleText('cyan', JSON.stringify(compatTargets[it])) }`) : '') }`));
+    } else console.log(styleText('green', 'nothing'));
+  }
+
+  if (filename !== null && filename !== undefined) {
+    await mkdir(dirname(filename), { recursive: true });
+    await writeFile(filename, script);
+  }
+
+  return { script };
+}

packages/core-js-builder/package.json

@@ -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.3"
   },
   "engines": {
-    "node": ">=20.19.0"
+    "node": "^20.19.0 || >=22.12.0"
   }
 }