From a76bec6297136fcaee1aaf9501ab3ef3e10e121e Mon Sep 17 00:00:00 2001
From: Roy Ivy III <rivy.dev@gmail.com>
Date: Mon, 28 Dec 2020 01:07:40 -0600
Subject: [PATCH] change/API! ~ add ESM module packaging

- adds an ESM wrapper to provide simple ESM support (as suggested in "Node Modules at War"

* ref: [Node Modules at War](https://redfin.engineering/node-modules-at-war-why-commonjs-and-es-modules-cant-get-along-9617135eeca1) @@ <https://archive.is/zl0qg>
* ref: [yargs ~ 'Road to ESM/Deno'](https://github.com/yargs/yargs/issues/1706)
---
 package.json                 | 12 ++++++++++++
 src/esm-wrapper/index.js     |  9 +++++++++
 src/esm-wrapper/package.json |  1 +
 src/index.ts                 | 12 +++++++++++-
 4 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 src/esm-wrapper/index.js
 create mode 100644 src/esm-wrapper/package.json

diff --git a/package.json b/package.json
index c3c5988..1dcb3ad 100644
--- a/package.json
+++ b/package.json
@@ -23,6 +23,17 @@
 	"main": "dist/cjs/index.js",
 	"module": "dist/cjs/esm-wrapper/index.js",
 	"types": "dist/types/index.d.ts",
+	"exports": {
+		"./package.json": "./package.json",
+		".": [
+			{
+				"import": "./dist/cjs/esm-wrapper/index.js",
+				"require": "./dist/cjs/index.js",
+				"types": "./dist/types/index.d.ts"
+			},
+			"./dist/cjs/index.js"
+		]
+	},
 	"keywords": [
 		"common",
 		"cross-platform",
@@ -44,6 +55,7 @@
 		"# build # build/compile package": "",
 		"build": "run-s _:regen:build",
 		"build:cjs": "tsc -p tsconfig/tsconfig.cjs.json",
+		"build:cjs/esm": "shx mkdir -p build/cjs && shx cp -r src/esm-wrapper build/cjs",
 		"## build:esm * [2020-12-22; rivy] TS compiles to ESMs are broken due to extension mishandling (use `rollup`)": "tsc -p tsconfig/tsconfig.esm.json",
 		"build:umd": "tsc -p tsconfig/tsconfig.umd.json",
 		"build:tests": "tsc -p tsconfig/tsconfig.tests.json",
diff --git a/src/esm-wrapper/index.js b/src/esm-wrapper/index.js
new file mode 100644
index 0000000..4746195
--- /dev/null
+++ b/src/esm-wrapper/index.js
@@ -0,0 +1,9 @@
+/* eslint-env node */
+// # spell-checker:ignore Deno
+
+import _ from '../index.js';
+// note: not usable by `deno`;
+//   ...`deno` is unable to load (the CJS module) '../index.js' via import => `'../index.js' does not provide an export named 'default'`
+
+const default_ = _;
+export default default_;
diff --git a/src/esm-wrapper/package.json b/src/esm-wrapper/package.json
new file mode 100644
index 0000000..6990891
--- /dev/null
+++ b/src/esm-wrapper/package.json
@@ -0,0 +1 @@
+{"type": "module"}
diff --git a/src/index.ts b/src/index.ts
index 9607bb3..fb0dfe2 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -3,7 +3,17 @@ import { default as default_ } from './lib/OSPaths';
 export * from './lib/OSPaths';
 export default default_;
 
-if (module) {
+const haveModuleExports_ = typeof module === 'object' && module.exports;
+if (haveModuleExports_) {
+	// enables direct require from CJS (eg, `const module = require('...');`), but generally disables any other exports
+	// * skipped for ESM (missing `module.exports`)
+	// * added non-enumerable '_esm!' property (as a hack) to allow full access to all exports (for testing, ...)
 	// eslint-disable-next-line functional/immutable-data
 	module.exports = default_;
+	Object.defineProperty(module.exports, '_esm!', {
+		get() {
+			return exports;
+		},
+		enumerable: false,
+	});
 }