caesars cipher freecodecamp
const rot13 = str => {
let decodedCipher = ''
// The number 65 represents A which also is the begining of our alphabets.
// The number 90 represents Z which also is the end of our alphabets.
// Space and any other non-alpha character is less than 65(A) and greater than 90(Z).
// Split and loop over every character
str.split('').forEach(character => {
// Get the integer or unicode for ever character which returns a number and store it in letterChar
const letterChar = character.charCodeAt()
// Check if number(letterChar) is less than 65(A) or greater than 90(Z)
// If true, return the number(letterChar) which means, it could be a non-alpha character
// If false, return the number(letterChar) + 13, which means it has shifted 13 places.
let unicode = letterChar < 65 || letterChar > 90 ? letterChar : letterChar + 13
// unicode minus 1 is greater or equal to 90(Z)
// Set unicode to equal unicode minus 1,
// we minus 1 cause unicode will give us the right operand instead of the left operand
// eg N + 13 will give us B instead of A, so,
// We substract the now(unicode-1) unicode from 90 to get the number left, then we add it to 65(A),
// Cause we start from begining after we've met the end
if((unicode - 1) >= 90) unicode = (((unicode - 1) - 90) + 65)
// Convert and add every character to cipher
decodedCipher += String.fromCharCode(unicode)
})
return decodedCipher;
}
rot13("GUR DHVPX OEBJA SBK WHZCF BIRE GUR YNML QBT.");
// With love @kouqhar