// A function that checks if a given string is a palindrome function isPalindrome(str) { str = str.toLowerCase().replace(/[^a-z0-9]+/g, ""); // Remove non-alphanumeric characters and convert to lowercase return str === str.split("").reverse().join(""); }

// Example usage console.log(isPalindrome("A man, a plan, a canal, Panama!")); // Output: true console.log(isPalindrome("Hello, world!")); // Output: false

// A class representing a basic calculator class Calculator { add(a, b) { return a + b; } subtract(a, b) { return a - b; } multiply(a, b) { return a * b; } divide(a, b) { if (b === 0) { throw new Error("Division by zero!"); } return a / b; } }

// Example usage const calc = new Calculator(); console.log(calc.add(2, 3)); // Output: 5 console.log(calc.divide(10, 2)); // Output: 5