Lock a Button with a Code Check

promocode.js

//Requires jquery
function regCodeComponent() {
  'use strict';

  var regController = {};
  
  var valid_codes = ['ramseynyc', 'sethsblog', 'garynyc'];
  
  regController.init = function (button) {
    regController.$button = $j(button);
    regController.$regContainer = regController.$button.parents('.registration');    
    regController.$promocode = regController.$regContainer.find('input.promocode');
    regController.$messagePanel = regController.$regContainer.find('.messagePanel');
    regController.$regContainer.on('click', regController.$button.selector, regController.click);
  };
  
  regController.click = function(a) {
    a.preventDefault();
    regController.show_error(false, '');
    var user_code = regController.$promocode.val().trim().toLowerCase();
    
    if (regController.code_exists(user_code)) {
      if (regController.is_valid_code(user_code)) {
        window.location.href = regController.$button.attr('href') + '/couponXXcode/' + user_code;
      } else {
        regController.show_error(true, 'Invalid code.');
      }
    } else {
      regController.show_error(true, 'Code is required.');
    }
  };
  
  regController.show_error = function(status, error_msg) {
    regController.$messagePanel.toggleClass('error', status).html(error_msg);
  }
  
  regController.code_exists = function(user_code) {
    var result = false;
    
    if (!!user_code) {
      result = true;
    }
    
    return result;
  };
  
  regController.is_valid_code = function(user_code) {
    var result = false;
    var i = 0;
    
    for (i; i < valid_codes.length; i++) {
      if (valid_codes[i].toLowerCase() === user_code) {
        result = true;
      }
    }
    
    return result;
  };

  return {
    init: regController.init
  };
}

(function (startRegController) {
  if (window.jQuery) { /* jQuery already loaded. Proceed. Otherwise wait until window.load */
    startRegController();
  } else if (window.addEventListener) { /*DOM method for binding an event */
    window.addEventListener('DOMContentLoaded', startRegController, false);
  } else if (window.attachEvent) { /* IE exclusive method for binding an event */
    window.attachEvent('onload', startRegController);
  } else if (document.getElementById) { /* support for older modern browsers */
    window.onload = startRegController;
  }
}(function () {
  var headerRegCode = new regCodeComponent();
  var bodyRegCode = new regCodeComponent();
  headerRegCode.init('.sectionHeader .event_summary .registration a.button');
  bodyRegCode.init('.sectionPrimary .event_summary .registration a.button');
}));