Grabbed dndbeyond's source code

```
~/go/bin/sourcemapper -output ddb -jsurl https://media.dndbeyond.com/character-app/static/js/main.90aa78c5.js
```

ddb_main/node_modules/@mui/base/utils/extractEventHandlers.js

@@ -0,0 +1,17 @@
+/**
+ * Extracts event handlers from a given object.
+ * A prop is considered an event handler if it is a function and its name starts with `on`.
+ *
+ * @param object An object to extract event handlers from.
+ * @param excludeKeys An array of keys to exclude from the returned object.
+ */
+export function extractEventHandlers(object, excludeKeys = []) {
+  if (object === undefined) {
+    return {};
+  }
+  const result = {};
+  Object.keys(object).filter(prop => prop.match(/^on[A-Z]/) && typeof object[prop] === 'function' && !excludeKeys.includes(prop)).forEach(prop => {
+    result[prop] = object[prop];
+  });
+  return result;
+}