feat(commonjs): add named exports option

Author: miomio-xiao

packages/vite-plugin-commonjs/README.md

@@ -30,6 +30,9 @@ export default {
 -  `include: string[]`
   Dependencies that only need to be transform.
 
+-  `addNamedExports: boolean`
+  add named exports.
+
 ### CommonJS module in node_modules
 ```js
 import { esbuildCommonjs } from '@originjs/vite-plugin-commonjs'

packages/vite-plugin-commonjs/__tests__/__snapshots__/transform.spec.ts.snap

@@ -0,0 +1,37 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`transform named exports 1`] = `
+"var __getOwnPropNames = Object.getOwnPropertyNames;
+var __commonJS = (cb, mod) => function __require() {
+  return mod || (0, cb[__getOwnPropNames(cb)[0]])((mod = { exports: {} }).exports, mod), mod.exports;
+};
+var require_stdin = __commonJS({
+  \\"<stdin>\\"(exports, module) {
+    const a = \\"a\\";
+    const obj = {
+      o1: 1,
+      o2: 2
+    };
+    module.exports = {
+      a,
+      b: \\"b\\",
+      ...obj
+    };
+    exports.c = \\"c\\";
+  }
+});
+
+    var __named_exports_for_vite = require_stdin();
+
+    var __named_exports_for_vite__a = __named_exports_for_vite['a'];
+var __named_exports_for_vite__b = __named_exports_for_vite['b'];
+var __named_exports_for_vite__o1 = __named_exports_for_vite['o1'];
+var __named_exports_for_vite__o2 = __named_exports_for_vite['o2'];
+var __named_exports_for_vite__c = __named_exports_for_vite['c'];
+
+    export {__named_exports_for_vite__a as a,__named_exports_for_vite__b as b,__named_exports_for_vite__o1 as o1,__named_exports_for_vite__o2 as o2,__named_exports_for_vite__c as c};
+    
+    export default __named_exports_for_vite;
+  
+"
+`;

packages/vite-plugin-commonjs/__tests__/transform.spec.ts

@@ -1,4 +1,4 @@
-import { transformRequire, isCommonJS } from "../src/lib";
+import { transformRequire, isCommonJS, transformCommonJS } from "../src/lib";
 
 test('transform require', () => {
     //general require
@@ -67,6 +67,30 @@ test('isCommonJS', () => {
     expect(isCommonJS(`exports['some key'] = 1`)).toBeTruthy();
 });
 
+test('transform named exports', () => {
+
+  let code = `
+    const a = 'a';
+
+    const obj = {
+      o1: 1,
+      o2: 2
+    };
+
+    module.exports = {
+      a,
+      b: 'b',
+      ...obj
+    };
+
+    exports.c = 'c';
+  `;
+  
+  const transformResult = transformCommonJS(code, true).code;
+  expect(transformResult).toMatch(/export {.*__named_exports_for_vite__a as a,.*}/);
+  expect(transformResult).toMatchSnapshot();
+});
+
 test('Both url and comments are present', () => {
   //singleline comments
   let code = `dosomething () {

packages/vite-plugin-commonjs/package.json

@@ -24,6 +24,7 @@
   },
   "homepage": "https://github.com/originjs/vite-plugins/tree/main/packages/vite-plugin-commonjs",
   "dependencies": {
+    "cjs-esm-exports": "^0.6.1",
     "esbuild": "^0.14.14"
   },
   "devDependencies": {

packages/vite-plugin-commonjs/src/index.ts

@@ -1,5 +1,5 @@
-import { transformSync, TransformResult } from "esbuild";
-import { transformRequire, isCommonJS } from "./lib";
+import { TransformResult } from "esbuild";
+import { transformRequire, transformCommonJS, isCommonJS } from "./lib";
 import * as fs from "fs";
 import { Plugin } from "vite";
 import createFilter from "./filter";
@@ -8,10 +8,11 @@ export type Options = {
   include?: string | string[] | undefined;
   exclude?: string | string[] | undefined;
   skipPreBuild?: boolean;
+  addNamedExports?: boolean;
 };
 
 export function viteCommonjs(
-  options: Options = { skipPreBuild: false }
+  options: Options = { skipPreBuild: false, addNamedExports: false }
 ): Plugin {
   const filter = createFilter(options.include, options.exclude);
   return {
@@ -28,7 +29,7 @@ export function viteCommonjs(
       let result = transformRequire(code, id);
 
       if (id.indexOf("/node_modules/.vite/") == -1 && isCommonJS(code)) {
-        return transformSync(result.code, { format: "esm" });
+        return transformCommonJS(result.code, options.addNamedExports);
       }
 
       if (result.replaced) {

packages/vite-plugin-commonjs/src/lib.ts

@@ -1,3 +1,6 @@
+import { parse as parseCjs } from 'cjs-esm-exports';
+import { transformSync } from 'esbuild';
+
 const commonJSRegex: RegExp = /\b(module\.exports|exports\.\w+|exports\s*=\s*|exports\s*\[.*\]\s*=\s*)/;
 const requireRegex: RegExp = /(?<!\.)\b_{0,2}require\s*\(\s*(["'].*?["'])\s*\)/g;
 const IMPORT_STRING_PREFIX: String = "__require_for_vite";
@@ -50,6 +53,54 @@ export function isCommonJS(code: string): boolean {
   return commonJSRegex.test(code);
 }
 
+export function transformCommonJS(code: string, addNamedExports = false) {
+  const transformResult = transformSync(code, { format: "esm" });
+
+  if (!addNamedExports) {
+    return transformResult;
+  }
+
+  const esmCode = transformResult.code;
+  const defaultExportRegex = /export default (.*?);/;
+  const defaultExport = esmCode.match(defaultExportRegex)?.[1];
+
+  if (!defaultExport) {
+    return transformResult;
+  }
+
+  const { exports } = parseCjs('', code);
+  if (!exports || !exports.length) {
+    return transformResult;
+  }
+
+  const namedKey = '__named_exports_for_vite';
+  const namedExportsMap: Record<string, string> = exports.reduce(
+    (map: Record<string, string>, key: string) => {
+      map[key] = `${namedKey}['${key}']`;
+      return map;
+    },
+    {},
+  );
+  const namedKeys = Object.keys(namedExportsMap);
+
+  const namedExportsCode = `
+    var ${namedKey} = ${defaultExport};
+
+    ${namedKeys.map(key => {
+      return `var ${namedKey}__${key} = ${namedExportsMap[key]};`
+    }).join('\n')}
+
+    export {${namedKeys.map(key => `${namedKey}__${key} as ${key}`).join(',')}};
+    
+    export default ${namedKey};
+  `;
+  
+  return {
+    ...transformResult,
+    code: esmCode.replace(defaultExportRegex, namedExportsCode),
+  };
+}
+
 function removeComments(
   code: string,
   exp: RegExp,
@@ -86,4 +137,4 @@ function isString(text: string) {
   } catch (err) {
     return false;
   }
-}
+}