Add CJS/ESM module exports (#81)

* add: rollup, esbuild and rollup plugins

- rollup
- @rollup/plugin-typescript
- rollup-plugin-dts
- rollup-plugin-esbuild
- esbuild

* update: tsconfig.json

Following changes:

- update lib and target to es2018
- add esModuleInterop and set to true
- add moduleResolution and set to node

* add: rollup config file

The configuration is designe to build:

- declarations
- cjs module
- esm module

* update: package.json exports and scripts

Set the correct entrypoint for cjs and esm modules and update build script to perform a typecheck followed by a rollup build

* update: typescript 4.4.2 -> 4.8.3

Update typescript to latest version due to an issue that version 4.4.2 has with rollup.
For reference here is the issue: [Builds hang with typescript 4.4.2](rollup/plugins#983)

* add: sideEffects to package.json

Add 'sideEffects: false' to package.json to allow webpack (and possible other bundlers) to threeshake the code

* fix: tsconfig target set to 'esnext'

Update tsconfig to target 'esnext' instead of 'es2018'

* fix: set rollup to preserve module structure

Set option 'preserveModules' to 'true' to keep module structure intact instead of combining everything into a single file.
This way it should be easier for bundlers to three shake unused code

* fix: tsconfig target and lib set to 'es2019'

Following the guidelines provided here: https://github.com/microsoft/TypeScript/wiki/Node-Target-Mapping, I set tsconfig target and lib to 'es2019' to support node 12

* fix: set package.json exports and use .cjs and .mjs extensions

Add exports and specific .cjs and .mjs extensions to make sure node uses the correct module loader
Following documentaion on the official nodejs website: https://nodejs.org/api/packages.html#dual-commonjses-module-packages

* build: bump rollup to 2.79.1

* build: regenerate yarn.lock

package.json

@@ -2,8 +2,15 @@
   "name": "radash",
   "version": "7.1.0",
   "description": "Functional utility library - modern, simple, typed, powerful",
-  "main": "dist/index.js",
+  "main": "dist/cjs/index.cjs",
+  "module": "dist/esm/index.mjs",
   "types": "dist/index.d.ts",
+  "exports": {
+    "import": "./dist/esm/index.mjs",
+    "require": "./dist/cjs/index.cjs",
+    "types": "./dist/index.d.ts"
+  },
+  "sideEffects": false,
   "files": [
     "dist/**/*"
   ],
@@ -16,18 +23,23 @@
   "scripts": {
     "test": "jest --coverage",
     "check": "yarn lint && yarn test && yarn build",
-    "build": "tsc",
+    "build": "yarn tsc --noEmit && yarn rollup -c",
     "lint": "tslint -p tsconfig.json"
   },
   "devDependencies": {
+    "@rollup/plugin-typescript": "^8.5.0",
     "@types/chai": "^4.2.21",
     "@types/jest": "^27.0.1",
     "chai": "^4.3.4",
+    "esbuild": "^0.15.7",
     "jest": "^27.1.0",
     "prettier": "^2.7.1",
     "prettier-plugin-organize-imports": "^3.0.3",
+    "rollup": "^2.79.1",
+    "rollup-plugin-dts": "^4.2.2",
+    "rollup-plugin-esbuild": "^4.10.1",
     "ts-jest": "^27.0.5",
     "tslint": "^6.0.0",
-    "typescript": "^4.4.2"
+    "typescript": "^4.8.3"
   }
 }

rollup.config.js

@@ -0,0 +1,85 @@
+// rollup.config.js
+import typescript from '@rollup/plugin-typescript';
+import dts from 'rollup-plugin-dts';
+import esbuild from 'rollup-plugin-esbuild';
+
+// Import dependencies
+import { builtinModules } from 'module';
+import { dependencies } from './package.json';
+
+const usePreferConst = true;      // Use "const" instead of "var"
+const usePreserveModules = true; // `true` -> keep modules structure, `false` -> combine everything into a single file
+const useStrict = true;           // Use "strict"
+const useThrowOnError = true;     // On error throw and exception
+const useSourceMap = true;        // Generate source map files
+const useEsbuild = true;          // `true` -> use esbuild, `false` use tsc
+
+// Node dependencies are treated as external dependencies and are not bundled
+const nodeDependencies = builtinModules
+  .filter((el) => !el.startsWith('_'))
+  .flatMap((el) => [el, `node:${el}`]);
+
+export default [
+  {
+    // .d.ts build
+    external: dependencies
+      ? [...Object.keys(dependencies), ...nodeDependencies]
+      : nodeDependencies,
+    input: 'src/index.ts',
+    output: {
+      file: 'dist/index.d.ts',
+      format: 'es',
+    },
+    plugins: [
+      dts(),
+    ],
+  },
+  {
+    // CJS build
+    external: dependencies
+      ? [...Object.keys(dependencies), ...nodeDependencies]
+      : nodeDependencies,
+    input: 'src/index.ts',
+    output: {
+      dir: 'dist/cjs',
+      format: 'cjs',
+      preferConst: usePreferConst,
+      preserveModules: usePreserveModules,
+      strict: useStrict,
+      entryFileNames: '[name].cjs',
+      sourcemap: useSourceMap,
+    },
+    plugins: [
+      useEsbuild
+        ? esbuild()
+        : typescript({
+            noEmitOnError: useThrowOnError,
+            outDir: 'dist/cjs'
+          }),
+    ],
+  },
+  {
+    // ESM build
+    external: dependencies
+      ? [...Object.keys(dependencies), ...nodeDependencies]
+      : nodeDependencies,
+    input: 'src/index.ts',
+    output: {
+      dir: 'dist/esm',
+      format: 'es',
+      preferConst: usePreferConst,
+      preserveModules: usePreserveModules,
+      strict: useStrict,
+      entryFileNames: '[name].mjs',
+      sourcemap: useSourceMap,
+    },
+    plugins: [
+      useEsbuild
+        ? esbuild()
+        : typescript({
+            noEmitOnError: useThrowOnError,
+            outDir: 'dist/esm'
+          }),
+    ],
+  },
+];

tsconfig.json

@@ -1,9 +1,10 @@
 {
   "compilerOptions": {
     "outDir": "dist",
-    "lib": ["es2016"],
-    "declaration": true,
-    "sourceMap": true
+    "moduleResolution": "node",
+    "target": "es2019",
+    "lib": ["es2019"],
+    "esModuleInterop": true,
   },
   "include": [
     "src/**/*.ts"