fix build script issue and also build es module (#5)

Author: natterstefan

.babelrc

@@ -12,4 +12,5 @@ tmp
 
 # build
 dist
+es
 lib

.gitignore

@@ -4,6 +4,16 @@ All notable changes to this project will be documented here. The format is based
 on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/) and this project
 adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Changed
+
+- build `es` version of the package as well (see [babel.config.js](./babel.config.js))
+
+### Fixed
+
+- fixed `build` script and `main` field issue, causing usage issues
+
 ## 2019/03/26 0.6.0
 
 ### Added

CHANGES.md

@@ -0,0 +1,32 @@
+/* eslint-disable sort-keys */
+// inspired by
+// - https://github.com/mui-org/material-ui/blob/b62015a61a4dfef72dfcb79cef917d701d50469f/babel.config.js
+let defaultPresets
+const environment = process.env.BABEL_ENV || 'umd'
+
+// We release a ES version of the package.
+// It's something that matches the latest official supported features of
+// JavaScript. Nothing more (stage-1, etc), nothing less (require, etc).
+if (environment === 'es') {
+  defaultPresets = []
+} else {
+  defaultPresets = [
+    [
+      '@babel/preset-env',
+      {
+        // note: we do not build "esm" (compared with material-ui example)
+        modules: ['umd'].includes(environment) ? false : 'commonjs',
+      },
+    ],
+  ]
+}
+
+module.exports = {
+  comments: false,
+  presets: [...defaultPresets, '@babel/preset-react'],
+  plugins: [
+    '@babel/plugin-transform-modules-commonjs',
+    '@babel/plugin-proposal-class-properties',
+    '@babel/plugin-proposal-object-rest-spread',
+  ],
+}

babel.config.js

@@ -4,17 +4,14 @@
   "license": "Apache-2.0",
   "version": "0.6.0",
   "description": "Manage a catalog (registry) of react-components easily.",
-  "main": "dist/index.js",
-  "module": "lib/index.js",
-  "sideEffects": false,
-  "files": [
-    "dist",
-    "lib"
-  ],
+  "main": "lib/index.js",
+  "module": "es/index.js",
+  "files": ["dist", "es", "lib"],
   "scripts": {
-    "build": "npm run build-lib && npm run build-umd",
-    "build-lib": "babel src --ignore */*.test.js,**/*.test.js --out-dir lib",
-    "build-umd": "webpack --mode=production",
+    "build": "npm run build-cjs && npm run build-es && npm run build-umd",
+    "build-cjs": "BABEL_ENV=cjs babel src --ignore */*.test.js,**/*.test.js --out-dir lib",
+    "build-es": "BABEL_ENV=es babel src --ignore */*.test.js,**/*.test.js --out-dir es",
+    "build-umd": "BABEL_ENV=umd webpack --mode=production",
     "coverage": "jest --coverage",
     "coveralls": "jest --coverage && cat ./coverage/lcov.info | coveralls",
     "lint": "eslint src",