QLScpt
A macOS QuickLook generator for .scpt files (both AppleScript and JavaScript).
This is already available in Spotlight as a Quick Look Preview Extension (selecting a .scpt file in Spotlight will show a preview, no matter if it is a JavaScript or AppleScript file). This new extension format is documented in this WWDC session.
Installation
$ brew cask install josh-/qlscpt/qlscpt