Let's say I have this folder structure:

parent
|-parent.html
|-parent.js
|-child
|--child.html
|--child.js

I want them to output in the same structure in my dist folder. By default this is what gets output:

dist/assets/parent.js
dist/assets/child.js

I want them to output like this:

dist/parent/parent.js
dist/parent/child/child.js

I tried changing the assetFileNames option of Rollup but it didn't do anything.