Check if filename exists and if so, count up for files of same name.

countFileName.js

  var i = 1;
  var array = fileName.split('.');
  var decryptFileName = `${array[0]}.${array[1]}`;
  while (fs.existsSync(`./decrypt-out/${decryptFileName}`)) {
    decryptFileName = `${array[0]} (${i}).${array[1]}`;
    i++;
  }