Add way to locally preview changes

[marekdedic]

Hi, I'd like to preview changes made to the library locally - at first, I thought that I could just serve the docs and see any changes that way, but it turns out the docs always use the version from jsdelivr... Is there any way to use the local version?

[Cweili]

My usual practice is to modify the script path in index.html to the local build result after building locally. Maybe this is a point worth optimizing.