Grabbed dndbeyond's source code

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

ddb_main/tools/js/CharacterSheet/selectors/composite/sheetApp.ts

@@ -0,0 +1,12 @@
+import { createSelector } from "reselect";
+
+import config from "~/config";
+
+import { appEnvSelectors } from "../../../Shared/selectors";
+
+const BASE_PATHNAME = config.basePathname;
+
+export const getBuilderUrl = createSelector(
+  [appEnvSelectors.getCharacterId],
+  (characterId) => `${BASE_PATHNAME}/${characterId}/builder/class/manage`
+);