How to write palindrome in JavaScript

Question

I wonder how to write palindrome in javascript, where I input different words and program shows if word is palindrome or not. For example word noon is palindrome, while bad

Answer 1

    function palindrome(str) {
        var re = /[^A-Za-z0-9]/g;
        str = str.toLowerCase().replace(re, '');
        var len = str.length;
        for (var i = 0; i < len/2; i++) {
            if (str[i] !== str[len - 1 - i]) {
                return false;
            }
        }
        return true;
    }