A function to check whether a string, stripped of non alphanumeric characters and spaces, is a palendrome

palindrome-checker.js

function palindrome(str) {
  const lettersOnlyRegex = /[a-zA-Z0-9]/g
  const letters = str.match(lettersOnlyRegex)

  if (null === letters || 0 === letters.length) {
    return false
  }

  const strippedString = str.match(lettersOnlyRegex).join('').toLowerCase()

  let reverse = ''
  let i = strippedString.length

  while (i-- > 0) {
    reverse += strippedString[i]
  }

  return reverse === strippedString;
}