Add format option to core-js-builder

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Changelog
 ##### Unreleased
 - Added `inverse` option to `core-js-compat`, [#1119](https://github.com/zloirock/core-js/issues/1119)
+- Added `format` option to `core-js-builder`, [#1120](https://github.com/zloirock/core-js/issues/1120)
 
 ##### [3.25.5 - 2022.10.04](https://github.com/zloirock/core-js/releases/tag/v3.25.5)
 - Fixed regression with an error on reuse of some built-in methods from another realm, [#1133](https://github.com/zloirock/core-js/issues/1133)

package.json

@@ -137,14 +137,15 @@
     "test-entries-basic": "zx tests/commonjs.mjs",
     "test-entries-content": "zx tests/commonjs-entries-content.mjs",
     "test-entries-standalone": "run-s init test-entries",
+    "test-builder": "zx tests/builder/builder.mjs",
     "test-compat-tools": "run-p test-compat-tool test-compat-targets-parser test-compat-get-modules-list-for-target-version",
     "test-compat-tool": "zx tests/compat-tools/compat.mjs",
     "test-compat-targets-parser": "zx tests/compat-tools/targets-parser.mjs",
     "test-compat-get-modules-list-for-target-version": "zx tests/compat-tools/get-modules-list-for-target-version.mjs",
     "test262": "test262-harness -t \"$(node -pe 'os.cpus().length')\" --host-args='--unhandled-rejections=none' --preprocessor=./tests/test262.js --prelude=./packages/core-js-bundle/index.js --test262-dir=node_modules/test262 'node_modules/test262/test/built-ins/**/*.js'",
-    "test": "run-s init test-lint bundle test-unit test-promises test-observables test-entries test-compat-tools check",
+    "test": "run-s init test-lint bundle test-unit test-promises test-observables test-entries test-compat-tools test-builder check",
     "ci-karma": "run-s init bundle test-unit-karma",
-    "ci-tests": "run-s init bundle test-unit-node test-promises test-observables test-entries test-compat-tools",
+    "ci-tests": "run-s init bundle test-unit-node test-promises test-observables test-entries test-compat-tools test-builder",
     "clean-dependencies": "node scripts/clean-dependencies.mjs",
     "refresh": "npm run clean-dependencies && npm it",
     "downloads": "zx scripts/downloads-by-versions.mjs",

packages/core-js-builder/README.md

@@ -12,13 +12,23 @@ For some cases could be useful to exclude some `core-js` features or generate a
 import builder from 'core-js-builder';
 
 const bundle = await builder({
-  modules: ['core-js/actual', 'esnext.reflect'],     // entries / modules / namespaces, by default - all `core-js` modules
-  exclude: [/^es\.math\./, 'es.number.constructor'], // a blacklist of entries / modules / namespaces, by default - empty list
-  targets: '> 0.5%, not dead, ie 9-11',              // optional browserslist or core-js-compat format query
-  summary: {                                         // shows summary for the bundle, disabled by default:
-    console: { size: true, modules: false },         // in the console, you could specify required parts or set `true` for enable all of them
-    comment: { size: false, modules: true },         // in the comment in the target file, similarly to `summary.console`
+  // entry / module / namespace / an array of them, by default - all `core-js` modules
+  modules: ['core-js/actual', /^esnext\.reflect\./],
+  // a blacklist of entries / modules / namespaces, by default - empty list
+  exclude: [/^es\.math\./, 'es.number.constructor'],
+  // optional browserslist or core-js-compat format query
+  targets: '> 0.5%, not dead, ie 9-11',
+  // shows summary for the bundle, disabled by default
+  summary: {
+    // in the console, you could specify required parts or set `true` for enable all of them
+    console: { size: true, modules: false },
+    // in the comment in the target file, similarly to `summary.console`
+    comment: { size: false, modules: true },
   },
-  filename: PATH_TO_MY_COREJS_BUNDLE,                // optional target filename, if it's missed a file will not be created
+  // 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',
+  // optional target filename, if it's missed a file will not be created
+  filename: PATH_TO_MY_COREJS_BUNDLE,
 });
 ```

packages/core-js-builder/index.js

@@ -29,44 +29,53 @@ module.exports = async function ({
   blacklist = null, // TODO: Obsolete, remove from `core-js@4`
   exclude = [],
   targets = null,
+  format = 'bundle',
   filename = null,
   summary = {},
 } = {}) {
+  if (!['bundle', 'cjs', 'esm'].includes(format)) throw TypeError('Incorrect output type');
   summary = { comment: normalizeSummary(summary.comment), console: normalizeSummary(summary.console) };
 
   const TITLE = filename != null ? filename : '`core-js`';
   let script = banner;
-  let code = '';
+  let code = '\n';
 
   const { list, targets: compatTargets } = compat({ targets, modules, exclude: exclude || blacklist });
 
   if (list.length) {
-    const tempFileName = `core-js-${ Math.random().toString(36).slice(2) }.js`;
-    const tempFile = join(tmpdir, tempFileName);
+    if (format === 'bundle') {
+      const tempFileName = `core-js-${ Math.random().toString(36).slice(2) }.js`;
+      const tempFile = join(tmpdir, tempFileName);
 
-    await webpack({
-      mode: 'none',
-      node: {
-        global: false,
-        process: false,
-        setImmediate: false,
-      },
-      entry: list.map(it => require.resolve(`core-js/modules/${ it }`)),
-      output: {
-        filename: tempFileName,
-        hashFunction: 'md5',
-        path: tmpdir,
-      },
-    });
+      await webpack({
+        mode: 'none',
+        node: {
+          global: false,
+          process: false,
+          setImmediate: false,
+        },
+        entry: list.map(it => require.resolve(`core-js/modules/${ it }`)),
+        output: {
+          filename: tempFileName,
+          hashFunction: 'md5',
+          path: tmpdir,
+        },
+      });
 
-    const file = await readFile(tempFile);
+      const file = await readFile(tempFile);
 
-    await unlink(tempFile);
+      await unlink(tempFile);
 
-    code = `!function (undefined) { 'use strict'; ${
-      // compress `__webpack_require__` with `keep_fnames` option
-      String(file).replace(/function __webpack_require__/, 'var __webpack_require__ = function ')
-    } }();`;
+      code = `!function (undefined) { 'use strict'; ${
+        // compress `__webpack_require__` with `keep_fnames` option
+        String(file).replace(/function __webpack_require__/, 'var __webpack_require__ = function ')
+      } }();\n`;
+    } else {
+      const template = it => format === 'esm'
+        ? `import 'core-js/modules/${ it }.js';\n`
+        : `require('core-js/modules/${ it }');\n`;
+      code = list.map(template).join('');
+    }
   }
 
   if (summary.comment.size) script += `/*\n * size: ${ (code.length / 1024).toFixed(2) }KB w/o comments\n */`;
@@ -81,9 +90,9 @@ module.exports = async function ({
 
   if (summary.console.modules) {
     console.log(`\u001B[32mbundling \u001B[36m${ TITLE }\u001B[32m, modules:\u001B[0m`);
-    for (const it of list) {
+    if (list.length) for (const it of list) {
       console.log(`\u001B[36m${ it + (targets ? ` \u001B[32mfor \u001B[36m${ JSON.stringify(compatTargets[it]) }` : '') }\u001B[0m`);
-    }
+    } else console.log('\u001B[36mnothing\u001B[0m');
   }
 
   if (filename != null) {

tests/builder/builder.mjs

@@ -0,0 +1,19 @@
+import { ok } from 'assert/strict';
+import builder from 'core-js-builder';
+
+const polyfills = await builder({
+  modules: 'core-js/actual',
+  exclude: [/group-by/, 'esnext.typed-array.to-spliced'],
+  targets: { node: 16 },
+  format: 'esm',
+});
+
+ok(polyfills.includes("import 'core-js/modules/es.error.cause.js';"), 'actual node 16 #1');
+ok(polyfills.includes("import 'core-js/modules/es.array.push.js';"), 'actual node 16 #2');
+ok(polyfills.includes("import 'core-js/modules/esnext.array.group.js';"), 'actual node 16 #3');
+ok(polyfills.includes("import 'core-js/modules/web.structured-clone.js';"), 'actual node 16 #4');
+ok(!polyfills.includes("import 'core-js/modules/es.weak-set.js';"), 'actual node 16 #5');
+ok(!polyfills.includes("import 'core-js/modules/esnext.weak-set.from.js';"), 'actual node 16 #6');
+ok(!polyfills.includes("import 'core-js/modules/esnext.array.group-by.js';"), 'actual node 16 #7');
+
+echo(chalk.green('builder tested'));