function caesarCipher(str, shift) {
if (shift < 0) {
return caesarCipher(str, shift + 26);
}

let encryptedText = '';

for (let i = 0; i < str.length; i++) {
let char = str[i];

if (char.match(/[A-Z]/)) {
encryptedText += String.fromCharCode((char.charCodeAt(0) - 65 + shift) % 26 + 65);
} else if (char.match(/[a-z]/)) {
encryptedText += String.fromCharCode((char.charCodeAt(0) - 97 + shift) % 26 + 97);
} else {
encryptedText += char;
}
}

return encryptedText;
}

let text = "Bonjour tout le monde!";
let shift = 3;
let encrypted = caesarCipher(text, shift);
console.log("Texte chiffré:", encrypted);