Replace babel-loader with swc-loader for webpack transpilation

babel.config.js

@@ -1 +1 @@
-module.exports = require('kolibri-build/babel.config');
+module.exports = require('kolibri-jest-config/jest.conf/babel.config');

kolibri/core/buildConfig.js

@@ -1,4 +1,5 @@
 // This is only used during build time, so OK to reference files outside of Kolibri src.
+const path = require('node:path');
 const { kolibriName } = require('kolibri-build');
 
 module.exports = [
@@ -11,6 +12,30 @@ module.exports = [
         libraryExport: 'default',
         libraryTarget: 'window',
       },
+      module: {
+        rules: [
+          {
+            // Use babel-loader only for the entry file that imports core-js,
+            // so that @babel/preset-env can expand `import 'core-js'` into
+            // granular polyfill imports based on the browserslist targets.
+            test: /\.(js|mjs)$/,
+            include: [path.resolve(__dirname, 'frontend/index.js')],
+            loader: 'babel-loader',
+            options: {
+              presets: [
+                [
+                  '@babel/preset-env',
+                  {
+                    useBuiltIns: 'entry',
+                    corejs: '3.31',
+                  },
+                ],
+              ],
+              sourceType: 'unambiguous',
+            },
+          },
+        ],
+      },
     },
   },
 ];

kolibri/core/package.json

@@ -4,7 +4,10 @@
   "private": true,
   "version": "0.0.1",
   "dependencies": {
+    "@babel/core": "^7.29.0",
+    "@babel/preset-env": "^7.29.2",
     "@vueuse/core": "catalog:",
+    "babel-loader": "^10.1.1",
     "browserslist-config-kolibri": "workspace:*",
     "core-js": "catalog:",
     "kolibri": "workspace:*",

package.json

@@ -91,6 +91,7 @@
       "vue-demi"
     ],
     "onlyBuiltDependencies": [
+      "@swc/core",
       "core-js",
       "deasync",
       "es5-ext",

packages/kolibri-build/package.json

@@ -1,6 +1,6 @@
 {
   "name": "kolibri-build",
-  "version": "1.0.0",
+  "version": "1.1.0",
   "description": "Build tools and webpack configuration for Kolibri",
   "repository": {
     "type": "git",
@@ -15,15 +15,11 @@
     "kolibri-build": "./src/cli.js"
   },
   "dependencies": {
-    "@babel/core": "^7.29.0",
-    "@babel/plugin-syntax-import-assertions": "^7.27.1",
-    "@babel/plugin-transform-runtime": "^7.29.0",
-    "@babel/preset-env": "^7.29.2",
+    "@swc/core": "^1.11.29",
+    "swc-loader": "^0.2.6",
     "autoprefixer": "10.4.23",
-    "babel-loader": "^10.1.1",
     "browserslist-config-kolibri": "0.18.0",
     "commander": "^14.0.3",
-    "core-js": "^3",
     "css-loader": "7.1.2",
     "css-minimizer-webpack-plugin": "7.0.4",
     "enhanced-resolve": "^5.20.1",

packages/kolibri-build/src/webpack.config.base.js

@@ -75,16 +75,23 @@ module.exports = ({ mode = 'development', hot = false, cache = false, transpile
   if (transpile) {
     rules.push({
       test: /\.(js|mjs)$/,
-      loader: require.resolve('babel-loader'),
+      loader: require.resolve('swc-loader'),
       exclude: [
         // From: https://webpack.js.org/loaders/babel-loader/#exclude-libraries-that-should-not-be-transpiled
         // \\ for Windows, / for macOS and Linux
         /node_modules[\\/]core-js/,
         /node_modules[\\/]webpack[\\/]buildin/,
       ],
       options: {
-        cacheDirectory: cache,
-        cacheCompression: false,
+        env: {
+          targets: require('browserslist-config-kolibri'),
+        },
+        jsc: {
+          parser: {
+            syntax: 'ecmascript',
+            importAssertions: true,
+          },
+        },
       },
     });
   }
@@ -108,9 +115,10 @@ module.exports = ({ mode = 'development', hot = false, cache = false, transpile
     optimization: {
       minimizer: [
         new TerserPlugin({
-          parallel: true,
+          minify: TerserPlugin.swcMinify,
           terserOptions: {
-            // Don't specify mangle, as it is true by default.
+            compress: true,
+            mangle: true,
             output: {
               comments: false,
             },

packages/kolibri-jest-config/jest.conf/babel.config.js

@@ -1,5 +1,13 @@
-const babelConfig = require('kolibri-build/babel.config');
-
-babelConfig.plugins.push('@babel/plugin-transform-runtime');
-
-module.exports = babelConfig;
+module.exports = {
+  presets: [
+    [
+      '@babel/preset-env',
+      {
+        useBuiltIns: 'entry',
+        corejs: '3.31',
+      },
+    ],
+  ],
+  plugins: ['@babel/plugin-syntax-import-assertions', '@babel/plugin-transform-runtime'],
+  sourceType: 'unambiguous',
+};

packages/kolibri-jest-config/package.json

@@ -12,11 +12,14 @@
   "private": false,
   "main": "jest.conf/index.js",
   "dependencies": {
+    "@babel/core": "^7.29.0",
+    "@babel/plugin-syntax-import-assertions": "^7.27.1",
     "@babel/plugin-transform-runtime": "^7.29.0",
+    "@babel/preset-env": "^7.29.2",
     "aphrodite": "^2.4.0",
+    "core-js": "^3",
     "intl": "^1.2.4",
     "kolibri": "workspace:*",
-    "kolibri-build": "workspace:*",
     "kolibri-design-system": "catalog:",
     "kolibri-logging": "workspace:*",
     "regenerator-runtime": "^0.14.1",