feat: use CJS module as ESM module in .mjs ✅

Author: xgqfrms

src/cjs-module.cjs

@@ -0,0 +1,18 @@
+const sum = (a, b) => a + b;
+
+// export = sum;
+// 'export =' can only be used in TypeScript files.ts(8003)
+
+// ❌
+// exports = sum;
+// obj = {}
+// sum = undefined
+
+// ✅
+// exports.sum = sum;
+// console.log(`module inner sum`, sum);
+
+// ✅
+// module.exports = sum;
+// ✅
+module.exports = {sum};

src/esm-module.mjs

@@ -0,0 +1,7 @@
+export const Add = (a, b) => a + b;
+
+// ✅
+// export default Add;
+
+// ✅
+export default {Add};

src/index.cjs

@@ -0,0 +1,30 @@
+const log = console.log;
+
+/* 
+const sum = require('./cjs-module.cjs');
+log(`sum =`, sum)
+// sum = [Function: sum]
+const result = sum(1,2);
+ */
+
+/* 
+const obj = require('./cjs-module.cjs');
+log(`obj =`, obj);
+// obj = { sum: [Function: sum] }
+const sum = obj.sum;
+ */
+
+const obj = require('./cjs-module.cjs');
+log(`obj =`, obj);
+
+const {sum} = require('./cjs-module.cjs');
+log(`sum =`, sum);
+// sum = [Function: sum]
+
+const result = sum(1,2);
+
+if(result === 3) {
+  log(`✅ sum(1,2) =`, result);
+} else {
+  log(`❌ error`, result);
+}

src/index.mjs

@@ -0,0 +1,43 @@
+const log = console.log;
+
+// ESM ✅
+// import Add from './esm-module.mjs';
+// import {Add as add} from './esm-module.mjs';
+// log(`Add =`, Add);
+// // Add = [Function: Add]
+// log(`add =`, add);
+// // add = [Function: Add]
+
+import ESM from './esm-module.mjs';
+import {Add as add} from './esm-module.mjs';
+log(`ESM =`, ESM);
+// ESM = { Add: [Function: Add] }
+log(`add =`, add);
+// add = [Function: Add]
+
+const test1 = ESM.Add(3,4);
+const test2 = add(3,4);
+
+if(test1 === 7 && test2 === 7) {
+  log(`🚀✅ ESM.Add(3,4) && add(3,4) =`, test1, test2);
+} else {
+  log(`🚀❌ error`, test);
+}
+
+
+// use CJS as ESM ✅
+import obj from './cjs-module.cjs';
+import {sum} from './cjs-module.cjs';
+
+log(`obj =`, obj);
+// obj = { sum: [Function: sum] }
+log(`sum =`, sum);
+// sum = [Function: sum]
+
+const result = sum(1,2);
+
+if(result === 3) {
+  log(`✅ sum(1,2) =`, result);
+} else {
+  log(`❌ error`, result);
+}