encrypt-decrypt.js

/**
Developer comment
- This is a pseudo-encryption algorithm which given a string S and an integer N concatenates all the odd-indexed 
characters of S with all the even-indexed characters of S, this process should be repeated N times.
- use recursive function
- decress the N
- every step encrypt the text
- make sure we have exist statement, than return the text
**/
function encrypt(text, n) {
  if(n <= 0 || text === null) {
    return text;
  }
  
  let arrayOfText = text.split('');
  let leftArray = arrayOfText.filter((word,index) => index%2);
  let rightArray = arrayOfText.filter((word,index) => !(index%2));
  
  text = leftArray.join('') + rightArray.join('');
  n--;
  return encrypt(text, n);
}

function decrypt(encryptedText, n) { 
  if(n <= 0 || encryptedText.trim() === '') {
    return encryptedText;
  }

  let cutAt = Math.floor(encryptedText.length/2);
  let leftArray = encryptedText.split('').splice(0,cutAt);
  let rightArray = encryptedText.split('').splice(cutAt);
  
  let newar = [];

  rightArray.map((value, key) => {
    newar.push(value)
    newar.push(leftArray[key]);
  });

  newar = newar.join('');

  n--;
  return decrypt(newar, n);
}