How to win the coding interview(blog.devmastery.com)

  > * @param {string} stringToTest - the string to test.

  >   // make sure we have a string.
  >    if (typeof stringToTest !== "string") {
  >

  > function isPalindrome(stringToTest) {
  >  ...
  >    // if we get here, it's a palindrome
  >    return true;

  function isPalindrome(str) {
    return (str.split("").reverse()).join("") == str;
  }

   function isPalindrome(text) {
       for (var i = 0; i <= text.length / 2; i++) {
           if (text[i] != text[text.length - i - 1]) return false;
       }
       return true;
   }

    import sys

    # the straightforward way, char-by-char compare

    def pal1(s):
        slen = len(s)
        slenm1 = slen - 1
        for i in xrange(slen/2):
            if s[i] != s[slenm1-i]:
                return False
        return True

    # s[:-5] === "the last 5 (or fewer) characters of s"
    # s[::] === s === s[start:end:incr], where start=0, end=len(s), and incr=1
    # s[::-1] === reverse(s) == s[end:start:incr], where start=0, end=len(s), and incr=-1

    def pal2(s):
        return s == s[::-1]

    # select which palindrome function to use
    pal = pal1

    # test with:
    # 1. null string
    # 2. single char (odd length)
    # 3. double char string (even length)

    if __name__ == '__main__':
        if len(sys.argv) != 2:
            print 'usage: pal <string>'
        else:
            s = sys.argv[1]
            if pal(s):
                print 'yep'
            else:
                print 'nope'

  >“Is this client side or server side JavaScript?”
  >“should an empty string be considered valid input?”
  >“Do I need to handle unicode characters?”

  'use strict'; // avoid ambiguity and sloppy errors

  /**
 * Tests whether or not a given string is a Palindrome
 * @param {string} stringToTest - the string to test.
 */

  function isPalindrome(stringToTest) {
    var start = 0,
        end;

    // make sure we have a string.
    if (typeof stringToTest !== "string") {
        // throw if we didn't get a string
        throw new TypeError("isPalindrome() expected a string, but got " +
            Object.prototype.toString.call(stringToTest) + " instead!");
    }

    // normalize string by lowercasing and removing non-word characters
    stringToTest = stringToTest
        .toLowerCase()
        .replace(/[^a-z0–9]/ig, '');

    if (stringToTest.length === 0) {
        // warn if we have no valid characters to test
        console.log("No valid characters to test, treated as empty string" +
            "\nStack: \n" + new Error().stack);
        return true; // an empty string is a palindrome.
    }

    end = stringToTest.length - 1;
    // Compare characters from outside in. Stop when we get to the middle.
    while (start < end) {
        if (stringToTest[start] !== stringToTest[end]) {
            return false;
        } else {
            start++;
            end--;
        }
    }

    // if we get here, it's a palindrome
    return true;

  // tests (should be in a separate file using a test framework)
  console.log(isPalindrome("something that is not a palindrome") + " = false");
  console.log(isPalindrome("something that is \n not a palindrome") + " = false");
  console.log(isPalindrome("race \n car") + " = true");
  console.log(isPalindrome("") + " = true + warn");
  console.log(isPalindrome("  ") + " = true + warn");
  console.log(isPalindrome("1221") + " = true");
  console.log(isPalindrome("0") + " = true");
  console.log(isPalindrome("racecar") + " = true");
  console.log(isPalindrome("No 'x' in Nixon!") + " = true");
  console.log(isPalindrome("~~!~!~") + " = true + warn");
  console.log(isPalindrome("Momsie") + " = false");
  console.log(isPalindrome(12)); // blow up
  console.log(isPalindrome(undefined)); // blow up
  console.log(isPalindrome(null)); // blow up