trying to build es6 together

CHANGELOG.md

@@ -3,6 +3,7 @@
 ## version 4.x (dev)
 
 - In order to enforce standard with C#, C++ and other related projects, we will adopt string base16 constructor ALWAYS as BigEndian. This removes the "strange" difference between building "0001" and "0x0001" (the former was not usually ONE... now it will be). In basic words `0x` prefix will be optional for string base16. Unfortunately, this may break compatibility with someone out there, so we will increase a MAJOR.
+- `npm run build` now puts two files in `dist/`: classic `csbiginteger.js` and `csbiginteger.mjs` (es6 module)
 
 ## version 3.x
 

package.json

@@ -5,7 +5,7 @@
   "main": "index.js",
   "scripts": {
     "test": "./node_modules/.bin/jest --coverage",
-    "build": "./node_modules/.bin/webpack"
+    "build": "./node_modules/.bin/webpack --config webpack.config.js && ./node_modules/.bin/webpack --config webpack-es6.config.js"
   },
   "repository": {
     "type": "git",

webpack-es6.config.js

@@ -0,0 +1,10 @@
+module.exports = {
+    mode: "production",
+    entry: "./index.js",
+    output: {
+      library: 'csbiginteger',
+      libraryTarget: 'var',
+      filename: './csbiginteger.mjs',
+      auxiliaryComment: 'csBigInteger.js library'
+    }
+}