Get the longest palindrome for a given string

palindrome.js

// example: node palindrome.js bananas

var input = process.argv[2];

if (!input || !input.length) {
  return '';
}

var longest = longestPalindrome(input);

console.log('Longest palindrome is: ' + longest);

function longestPalindrome(input) {
  var word;

  for (var i = input.length; i > 0; i--) {
    for (var j = 0; j+i <= input.length; j++) {
      word = input.slice(j, i+j);

      if (word && mirrors(word)) {
        return word;
      }
    }
  }

  // default to first letter
  return input[0];
}

function mirrors(word) {
  return word === word.split('').reverse().join('');
}

This code doesn't account for whitespaces and but if you want to send a whole sentence like "Are we not drawn onward to new era" you should strip whitespaces .replace(/ /g,'') and use .toLowerCase() to make it work.

Another note is if you call app and give it a sentence like:
node palindrome.js This is my sentence it will only check This for palindrome.

Correct way would be to call it as
node palindrome.js "This is my sentence" and replace all whitespaces and turn your string to lowecase for comparation