This does not work. Simple encode & decoder

failedJSEncoding.js

// This would be hosted on the server but node does not support atob btoa.
function decode(toDecode){ // eslint-disable-line no-unused-vars
  let salt = 'MySimpleSalt';
  let decoded = atob(toDecode);
  if (toDecode === btoa(decoded)){
    return decoded.replace(salt,'');
  }
  throw new Error('Could not decode data');
}

function encode(toEncode){ // eslint-disable-line no-unused-vars
  let salt = 'MySimpleSalt';
  let encoded = btoa(toEncode + salt);
  if ((toEncode + salt) === atob(encode)){
    return encoded;
  }
  throw new Error('Could not encode data');
}