Encrypts or decrypts a given string using the Caesar cipher.
- Use the modulo (
%
) operator and the ternary operator (?
) to calculate the correct encryption/decryption key. - Use the spread operator (
...
) andArray.prototype.map()
to iterate over the letters of the given string. - Use
String.prototype.charCodeAt()
andString.fromCharCode()
to convert each letter appropriately, ignoring special characters, spaces etc. - Use
Array.prototype.join()
to combine all the letters into a string. - Pass
true
to the last parameter,decrypt
, to decrypt an encrypted string.
const caesarCipher = (str, shift, decrypt = false) => { const s = decrypt ? (26 - shift) % 26 : shift; const n = s > 0 ? s : 26 + (s % 26); return [...str] .map((l, i) => { const c = str.charCodeAt(i); if (c >= 65 && c <= 90) return String.fromCharCode(((c - 65 + n) % 26) + 65); if (c >= 97 && c <= 122) return String.fromCharCode(((c - 97 + n) % 26) + 97); return l; }) .join(''); };
Examples
caesarCipher('Hello World!', -3); // 'Ebiil Tloia!' caesarCipher('Ebiil Tloia!', 23, true); // 'Hello World!'
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