odin-javascript-exercises/09_palindromes/solution/palindromes-solution.js

const palindromes = function (string) {
  // Since we only consider letters and numbers, create a variable containing all valid characters
  const alphanumerical = 'abcdefghijklmnopqrstuvwxyz0123456789';

  // Convert to lowercase, split to array of individual characters, filter only valid characters, then rejoin as new string
  const cleanedString = string
    .toLowerCase()
    .split('')
    .filter((character) => alphanumerical.includes(character))
    .join('');

  // Create a new reversed string for comparison
  const reversedString = cleanedString.split('').reverse().join('');

  // Return the outcome of the comparison which will either be true or false
  return cleanedString === reversedString;
};

module.exports = palindromes;