Copy new files between Google Drive folders

// Google script to copy new files from SourceFolder to DestFolder.
// Script checks/skips if file exists in DestFolder with identical name to file from SourceFolder.
// Replace bogus folder IDs in script with correct folder IDs for your folders (look at the URL for a folder).
function CopyNewFiles() {
  var SourceFolder = DriveApp.getFolderById('JMtgsgM9sY9Fe5Z7wCbb4YVVqfeZiZ');
  var SourceFiles = DriveApp.getFolderById('JMtgsgM9sY9Fe5Z7wCbb4YVVqfeZiZ').getFiles();
  var DestFolder = DriveApp.getFolderById('SFGXwgvX6DmkAvPrrnWC2KY3imy7s2');
  var DestFiles = DriveApp.getFolderById('SFGXwgvX6DmkAvPrrnWC2KY3imy7s2').getFiles();
  var NotInDest = true;
  while (SourceFiles.hasNext()) {
    SourceFile = SourceFiles.next();
    while (DestFiles.hasNext()) {
      DestFile = DestFiles.next();
      if (SourceFile.getName() === DestFile.getName()) {
        NotInDest = false;
        break;
      }
    }
    if (NotInDest) {
      SourceFile.makeCopy(SourceFile.getName(), DestFolder);
    }
    NotInDest = true;
    DestFiles = DriveApp.getFolderById('SFGXwgvX6DmkAvPrrnWC2KY3imy7s2').getFiles();
  }
}