Modules Course - Message Mixer Project - step 6

I input ‘node message-mixer.js caesar 4’ into the terminal and am getting the following error message:

$ node message-mixer.js caesar 4
/home/ccuser/workspace/modules-message-mixer/encryptors.js:41
for (let i = 0; i < str.length; i++) {
^

TypeError: Cannot read property ‘length’ of undefined
at Object.symbolCipher (/home/ccuser/workspace/modules-message-mixer/encryptors.js:41:26)
at Object. (/home/ccuser/workspace/modules-message-mixer/message-mixer.js:10:33)
at Module._compile (module.js:571:32)
at Object.Module._extensions…js (module.js:580:10)
at Module.load (module.js:488:32)
at tryModuleLoad (module.js:447:12)
at Function.Module._load (module.js:439:3)
at Module.runMain (module.js:605:10)
at run (bootstrap_node.js:427:7)
at startup (bootstrap_node.js:151:9)

message-mixer tab info:

// Import the functions from encryptors.js here.

const encryptors = require('./encryptors.js');

// Encryption Functions
/////////////////////////////////////////////

const caesarCipher = encryptors.caesarCipher('Hello', 6);

const symbolCipher = encryptors.symbolCipher();

const reverseCipher = encryptors.reverseCipher();

// User Input / Output Logic
/////////////////////////////////////////////

const encryptionMethod = getEncryptionMethod();
process.stdin.on('data', (userInput) => {
  displayEncryptedMessage(encryptionMethod, userInput);
});

/* Helper function for determining which cipher method
the user chose when they ran the program. */
function getEncryptionMethod() {
  let encryptionMethod;
  
  const encryptionType = process.argv[2];  
  if (encryptionType === 'symbol') {
    encryptionMethod = symbolCipher;
  } else if (encryptionType === 'reverse') {
    encryptionMethod = reverseCipher;
  } else if (encryptionType === 'caesar') {
    let amount = Number(process.argv[3]);
    if (Number.isNaN(amount)) {
      process.stdout.write(`Try again with a valid amount argument. \n`)
      process.exit();  
    }
    encryptionMethod = (str) => caesarCipher(str, amount);
  } 
  else {
    process.stdout.write(`Try again with a valid encryption type. \n`)
    process.exit();
  }

  process.stdout.write('Enter the message you would like to encrypt...\n> ');
  return encryptionMethod;
}

/* Helper function for displaying the encrypted message to the user. */
function displayEncryptedMessage(encryptionMethod, userInput) {
  let str = userInput.toString().trim();    
  let output = encryptionMethod(str);
  process.stdout.write(`\nHere is your encrypted message:\n> ${output}\n`)
  process.exit();
}

encryptors tab info:

const caesarCipher = (str, amount = 0) => {
  if (amount < 0) {
    return caesarCipher(str, amount + 26);
  }
  let output = '';
  for (let i = 0; i < str.length; i++) {
    let char = str[i];
    if (char.match(/[a-z]/i)) {
      let code = str.charCodeAt(i);
      if (code >= 65 && code <= 90) {
        char = String.fromCharCode(((code - 65 + amount) % 26) + 65);
      } else if (code >= 97 && code <= 122) {
        char = String.fromCharCode(((code - 97 + amount) % 26) + 97);
      }
    }
    output += char;
  }
  return output;
};

const symbolCipher = (str) => {
  const symbols = {
    'i': '!',
    '!': 'i',
    'l': '1',
    '1': 'l',
    's': '$',
    '$': 's',
    'o': '0',
    '0': 'o',
    'a': '@',
    '@': 'a',
    'e': '3',
    '3': 'e',
    'b': '6',
    '6': 'b'
  }

  let output = '';
  for (let i = 0; i < str.length; i++) {
    let char = str.toLowerCase()[i];

    if (symbols[char]) {
      output += symbols[char]
    } else {
      output += char;
    }
  }
  return output;
}

const reverseCipher = (sentence) => {
  let words = sentence.split(' ');
  for (let i = 0; i < words.length; i++) {
    words[i] = words[i].split('').reverse().join('');
  }
   return words.join(' ');
};

module.exports.caesarCipher = caesarCipher;

module.exports.symbolCipher = symbolCipher;

module.exports.reverseCipher = reverseCipher;

Hello, @chip1140778532, and welcome to the forums!

What is the purpose of the above lines?

hello! I added those via step 5:

Extract the three encyrption methods from encryptors and store them in three variables: caesarCipher , symbolCipher , and reverseCipher .

Okay. This is a case of wanting to do one thing, but unknowingly doing something else. What happens when you include ()'s at the end of a function name?

Okay, I’m still confused. I read chip1140778532 problem and the same thing happened to me. could you please explain why you added the ‘Hello’ and the number and how to fix it. Thanks.

I just figured it out. you just have to remove the bracket and everything in them. then type the node message-mixer thing.

1 Like