This is an alphanumeric less than evaluator. It works on strings and numbers passed as arguments. When evaluating alphanumeric strings (string-1, string-2), it tests the string portion for equality, and if equal begins testing the numeric portion at the end.

AlphaNumeric less than.js

/**
 * Routine to compare numbers or strings and combinations thereof in terms
 * of string1 < string2
 *
 * @param  {Number|String} string1 First item to compare
 * @param  {Number|String} string2 Second item to compare
 * @return {Boolean}         True if string1 < string2, else false.
 */
var lessThan = function(string1, string2) {
  // handle generic numbers
  if (typeof (string1) === 'number' && typeof (string2) === 'number') {
    return string1 < string2;
  }
  // else we need to compare some strings!
  string1 = string1.toLowerCase();
  string2 = string2.toLowerCase();
  // only match if at the end of string, eg. item, item-1, item-2, etc.
  var regex = /([0-9]+)$/g;
  var alpha1 = string1.split(regex);
  var num1 = string1.match(regex);
  var alpha2 = string2.split(regex);
  var num2 = string2.match(regex);

  // if there are no numerical parts to our strings, simply return the
  // result
  if (num1 === null && num2 === null) {
    return (string1 < string2);
  }
  // else we need to test these strings

  // total the numeric portions
  var total1 = 0;
  if (num1 !== null) {
    total1 = parseInt(num1.join(''), 10);
  }
  var total2 = 0;
  if (num2 !== null) {
    total2 = parseInt(num2.join(''), 10);
  }
  if (alpha1[0] == alpha2[0]) {
    return (total1 < total2);
  } else {
    return (alpha1[0] < alpha2[0]);
  }
};