refactor: simplify with Rollup config file

Author: brettz9

constructor/build.js

@@ -23,7 +23,8 @@
   "license": "MIT",
   "scripts": {
     "test": "node test/run.js",
-    "prepublishOnly": "node constructor/build.js"
+    "build": "rollup -c",
+    "prepublishOnly": "npm run build"
   },
   "peerDependencies": {
     "acorn": "^6.0.0 || ^7.0.0 || ^8.0.0"

package.json

@@ -0,0 +1,10 @@
+export default {
+  input: "index.js",
+  external: ["acorn"],
+  output: {
+    file: "index.cjs",
+    exports: 'default',
+    format: "cjs",
+    banner: "// DO NOT edit this file, it's auto-generated from 'rollup.config.js'; any changes will be overwritten. \n"
+  }
+};