rollup config

package.json

@@ -1,8 +1,10 @@
 {
   "private": true,
+  "type": "module",
   "version": "beeeeeeta",
   "scripts": {
-    "build": "rm -rf ./dist/ && rollup src/js/main.js --file dist/engine-$(npm pkg get version | tr -d '\"').js --format es",
+    "build": "rollup --config rollup.config.js",
+    "watch": "ROLLUP_WATCH=true rollup --config rollup.config.js --watch",
     "prettier-check": "prettier --check .",
     "prettier-write": "prettier --write .",
     "editorconfig-check": "ec -exclude 'node_modules' .",

rollup.config.js

@@ -0,0 +1,9 @@
+import pkg from './package.json' assert { type: 'json' };
+
+export default {
+  input: 'src/main.js',
+  output: {
+    file: `dist/engine-${pkg.version}.js`,
+    format: 'es',
+  },
+};