love_tracks.js

(function() {
  var currentApp = Application.currentApplication()
  currentApp.includeStandardAdditions = true

  if (currentApp.systemInfo().systemVersion >= "10.15") {
    var musicApp = Application("Music")
  } else {
    var musicApp = Application("iTunes")
  }

  var markTrack = (track, shouldLove) => {
    if (shouldLove) {
      track.loved = shouldLove
      return "Loved: " + track.name()
    } else {
      track.loved = shouldLove
      return "Unloved: " + track.name()
    }
  }

  var shouldLove = "{query}" == "true"

  if (currentApp.name == musicApp.name) {
    var selection = musicApp.selection()
    if (selection.length > 0) {
      selection.forEach(track => {
        markTrack(track, shouldLove)
      })
    
      return "Loved: " + selection.map(t => t.name()).join(" & ")
    } else {
      return markTrack(musicApp.currentTrack(), shouldLove)
    }
  } else {
    return markTrack(musicApp.currentTrack(), shouldLove)
  }
})()