Need help with Coding question: Javascript Syntax Classes

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1

Hi everyone,
I’m stuck on the answer to question 3 of this Javascript Quiz
I tried to test again and again the problem pop-up when I checked the answer, my codes work fine for the test, but it keeps saying something wrong.
Did I miss something here?

A shift cipher takes a plain text message and shifts each letter forward in the alphabet by a given number. For example, a shift cipher with a shift of 1 would turn the string 'hello' to 'ifmmp'.

Create a class ShiftCipher that takes the numerical value of the shift as a constructor parameter. The class should have two methods:

  • encrypt: takes a plain text string and returns a capitalized string with each letter shifted forward in the alphabet based on the set shift value.
  • decrypt: takes an encrypted message and returns a lower case string with each letter shifted back in the alphabet based on the set shift value.
  • In both methods, any character outside the alphabet should remain the same.
  • But if a character is shifted outside the alphabet in either direction it should be wrapped around to the other side. For example, encrypting a y with a shift of 4 results in C and decrypting an A with a shift of 1 result in z.

Example:

const cipher = new ShiftCipher(2);
cipher.encrypt('I love to code!'); // returns 'K NQXG VQ EQFG!'
cipher.decrypt('K <3 OA RWRRA'); // returns 'i <3 my puppy'

Feel free to reference the Unicode Table as well as the JavaScript String methods including: toUpperCase(), toLowerCase(), charCodeAt() and fromCharCode()

This is my solution:

// Write class below
class ShiftCipher {
  constructor(number) {
    this._number = number;
  }
  encrypt(string) {
    let upperString = string.toUpperCase();
    let charCode = [];
    for (let i = 0; i<upperString.length;i++) {
      charCode.push(upperString[i].charCodeAt());
    }
     let newCharCode = charCode.map(x => {
      if (x > 64 && x < 91 && this._number > 90-x) {
        return 64 + this._number -(90-x);
      } else if (x > 64 && x < 91) {
        return x + this._number;
      } else return x ;
    })
    let newString = "";
    newCharCode.forEach(x => newString += String.fromCharCode(x));
    return console.log(newString);
  }

  decrypt(string) {
    let lowerString = string.toLowerCase();
    let charCode = [];
    for (let i = 0; i<lowerString.length;i++) {
    charCode.push(lowerString[i].charCodeAt());
}
  let newCharCode = charCode.map(x => {
    if (x > 96 && x < 123 && this._number > x - 96) {
      return 122 - (this._number - (x - 96));
    } else if (x > 96 && x < 123) {
      return x - this._number;
    } else return x;
  })
  let newString = "";
  newCharCode.forEach(x => newString += String.fromCharCode(x))
  return console.log(newString);
  }
}

const cipher = new ShiftCipher(2);
cipher.encrypt('I love to code!'); // returns 'K NQXG VQ EQFG!'
cipher.decrypt('K <3 OA RWRRA'); // returns 'i <3 my puppy'
3

You have
return console.log(newString);
at the end of your functions
but console.log does not return anything, so your function doesn’t return anything (besides undefined)

Change that to
return newString;
or to
console.log(newString);
return newString;
so that the functions return newString

2 Likes
4

Yes, thank you.
And the problem I found in the first if condition for the decrypt method should add 1 more equal sign “=” to

if (x > 96 && x < 123 && this._number >= x - 96)

It is working now!