backup and delete original files by size in target directory - cleanup reddit wallpaper stash populated by IFTTT

move_by_size.gs

function wallpaper_cleanup() {
  var folder = DriveApp.getFoldersByName("wallpapers").next();
  var small_folder = DriveApp.getFoldersByName("small_wallpapers").next();
  var files = folder.getFiles();
  while (files.hasNext()) {
    var file = files.next();
    if (file.getSize() < 200000) {
      file.makeCopy(small_folder);
      file.setTrashed(true);
      Logger.log(file.getName() + file.getSize());
    }
  }
}