Lists unique tags across multiple files. To be used with Shortcuts.

List Tags.js

let fm = FileManager.iCloud()
let filePaths = args.fileURLs
let tags = filePaths.reduce((cur, e) => {
  return cur.concat(fm.allTags(e))
}, [])
let uniqueTags = tags.filter((t, idx) => {
  return tags.indexOf(t) === idx
})
let output = {"tags": uniqueTags}
Script.setShortcutOutput(output)
Script.complete()