Caesar Cipher - spaces and other characters

Question

I have created a Caesar Cipher code below but I want the returned string to include spaces and other characters. I've tried regex but this does not seem to solve the problem or maybe i'm not using it right, I'm not too sure.

Any help appreciated. Thanks!

function caesarCipher(str, n) {
  let newStr = '';
  let alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('')
  let regex = /[a-z]/

  for (let i = 0; i < str.length; i++) {
    if (str[i].match(regex) === false) {
      newStr += str[i]
      continue;
    }
    let currentIndex = alphabet.indexOf(str[i]);
    let newIndex = currentIndex + n;
    newStr += alphabet[newIndex];
  }
  return newStr
}

console.log(caesarCipher('ebiil tloia!', 3)) //should return hello world! but returns hellocworldc

It doesn't return `hellocworldc`. It returns an indefinite amount of `undefined`. — Jack Bashford, May 27 '19 at 00:45

helloitsjoe · Accepted Answer · 2019-05-27T00:56:31.807

2

RegExp.test returns a boolean, String.match returns an array. This line:

if (str[i].match(regex) === false) {

should be

if (regex.test(str[i]) === false) {

This should catch any value that's not a lowercase letter (spaces, punctuation, etc) - If you want to encode uppercase too, add the i flag at the end of the regex: /[a-z]/i

edited May 27 '19 at 00:56

answered May 27 '19 at 00:51

helloitsjoe

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score 0 · Answer 2 · answered May 27 '19 at 00:49

Firstly, you need to pass the shift (3) to the function. Secondly, since there are no spaces in alphabet, you need to add a test:

function caesarCipher(str, n) {
  let newStr = '';
  let alphabet = 'abcdefghijklmnopqrstuvwxyz'.split('')
  let regex = /[a-z]/

  for (let i = 0; i < str.length; i++) {
    if (str[i].match(regex) === false) {
      newStr += str[i]
    }
    let currentIndex = alphabet.indexOf(str[i]);
    if (!(currentIndex + 1)) {
      newStr += " ";
    } else {
      let newIndex = currentIndex + n;
      newStr += alphabet[newIndex];
    }
  }
  return newStr
}

console.log(caesarCipher('ebiil tloia!', 3)) //should return hello world! but returns hellocworldc

Caesar Cipher - spaces and other characters

2 Answers2