full-palindrome.js

const string1 = 'level';
const string2 = 'Le, vel.';

const isPalindrome = stringToTest => {
  const stringTransformed = stringToTest
      .replace(/[^\w]/gi, '') // replace all non-letter characters
      .toLowerCase(); // make all characters lower cased

  return stringTransformed === stringTransformed.split('').reverse().join('');
}

isPalindrome(string1); // true
isPalindrome(string2); // true