Rollup changes

rollup.config.js

@@ -0,0 +1,52 @@
+import resolve from "@rollup/plugin-node-resolve";
+import commonjs from "@rollup/plugin-commonjs";
+import babel from "@rollup/plugin-babel";
+import { terser } from "rollup-plugin-terser";
+import json from '@rollup/plugin-json';
+
+const commonConfig = {
+    input: 'src/index.js',
+    output: {
+        name: 'repertory-js',
+        sourcemap: true
+    },
+    plugins: [
+        resolve({
+            customResolveOptions: {
+                moduleDirectory: 'node_modules'
+            }
+        }),
+        babel({
+            exclude: 'node_modules/**',
+            babelHelpers: 'runtime'
+        }),
+        commonjs(),
+        json()
+    ]
+};
+
+// ESM config
+const esmConfig = Object.assign({}, commonConfig);
+esmConfig.output = Object.assign({}, commonConfig.output, {
+    file: 'dist/mjs/repertory-js.mjs',
+    format: 'esm'
+});
+
+// ESM prod config
+const esmProdConfig = Object.assign({}, esmConfig);
+esmProdConfig.output = Object.assign({}, esmConfig.output, {
+    file: 'dist/mjs/repertory-js.min.mjs',
+    sourcemap: false
+});
+esmProdConfig.plugins = [
+    ...esmConfig.plugins,
+    terser()
+];
+
+let configurations = []; 
+configurations.push(
+    esmConfig,
+    esmProdConfig
+)
+
+export default configurations;