Convert to ESM

rollup.config.js

@@ -0,0 +1,17 @@
+// See: https://rollupjs.org/introduction/
+
+import commonjs from '@rollup/plugin-commonjs'
+import { nodeResolve } from '@rollup/plugin-node-resolve'
+
+const config = {
+  input: 'src/index.js',
+  output: {
+    esModule: true,
+    file: 'dist/index.js',
+    format: 'es',
+    sourcemap: true
+  },
+  plugins: [commonjs(), nodeResolve()]
+}
+
+export default config