add minification to builder, move from terser to swc

Author: zloirock

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/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

@@ -35,6 +35,7 @@ export default async function ({
   exclude = [],
   targets = null,
   format = 'bundle',
+  minify = true,
   filename = null,
   summary = {},
 } = {}) {
@@ -81,16 +82,48 @@ export default async function ({
       }
 
       // rolldown helpers / wrappers contain es2015 syntax
-      code = (await transform(code, {
+      const swcOptions = {
         env: {
           include: [
             'transform-arrow-functions',
             'transform-shorthand-properties',
           ],
         },
-      })).code;
+      };
+
+      if (minify) Object.assign(swcOptions, {
+        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,
+            },
+          },
+        },
+      });
+
+      code = (await transform(code, swcOptions)).code;
 
-      code = `!function (undefined) { 'use strict'; ${ code } }();\n`;
+      // swc considers output code as a module and drops 'use strict`
+      code = `!function () { 'use strict'; ${ code } }();\n`;
     } else {
       code = importModules(list, format);
     }

scripts/bundle-package/bundle-package.mjs

@@ -1,57 +1,24 @@
-import { minify } from 'terser';
 import builder from '@core-js/builder';
-import config from '@core-js/builder/config.mjs';
 
 const { cyan, green } = chalk;
 const ESMODULES = argv._.includes('esmodules');
 const BUNDLED_NAME = argv._.includes('bundled-name') ? argv._[argv._.indexOf('bundled-name') + 1] : 'index';
 const MINIFIED_NAME = argv._.includes('minified-name') ? argv._[argv._.indexOf('minified-name') + 1] : 'minified';
 const PATH = 'packages/core-js-bundle/';
 
+const options = ESMODULES ? { targets: { esmodules: true } } : {};
+
 function log(kind, name, code) {
   const size = (code.length / 1024).toFixed(2);
   echo(green(`${ kind }: ${ cyan(`${ PATH }${ name }.js`) }, size: ${ cyan(`${ size }KB`) }`));
 }
 
-async function bundle({ bundled, minified, options = {} }) {
-  const { script } = await builder({ modules: 'full', ...options });
-
-  log('bundling', bundled, script);
-  await fs.writeFile(`${ PATH }${ bundled }.js`, script);
+const { script } = await builder({ modules: 'full', minify: false, ...options });
 
-  const { code, map } = await minify(script, {
-    ecma: 5,
-    safari10: true,
-    keep_fnames: true,
-    compress: {
-      hoist_funs: true,
-      hoist_vars: true,
-      passes: 2,
-      pure_getters: true,
-      // document.all detection case
-      typeofs: false,
-      unsafe_proto: true,
-      unsafe_undefined: true,
-    },
-    format: {
-      max_line_len: 32000,
-      preamble: config.banner,
-      webkit: true,
-      // https://v8.dev/blog/preparser#pife
-      wrap_func_args: false,
-    },
-    sourceMap: {
-      url: `${ minified }.js.map`,
-    },
-  });
+log('bundling', BUNDLED_NAME, script);
+await fs.writeFile(`${ PATH }${ BUNDLED_NAME }.js`, script);
 
-  await fs.writeFile(`${ PATH }${ minified }.js`, code);
-  await fs.writeFile(`${ PATH }${ minified }.js.map`, map);
-  log('minification', minified, code);
-}
+const { script: minified } = await builder({ modules: 'full', minify: true, ...options });
 
-await bundle({
-  bundled: BUNDLED_NAME,
-  minified: MINIFIED_NAME,
-  options: ESMODULES ? { targets: { esmodules: true } } : {},
-});
+await fs.writeFile(`${ PATH }${ MINIFIED_NAME }.js`, minified);
+log('bundling minified', MINIFIED_NAME, minified);