Shopify Checkout Hack - This scipt helps to modify the Shopify Checkout Pages

Shopify-Checkout-Hack.js

/**
 * Shopify Checkout Hack
 *
 * This scipt helps to modify the Shopify Checkout Pages. To run this script, add your
 * code for each checkout step, compress your code with a tool of your choice and paste
 * it to:
 *
 *    Admin > General > Google Analytics > Additional Google Analytics Javascript
 *
 * @author Christoph Vieth <christoph@vieth.me>
 * @copyright Copyright (c) 2015 - Christoph Vieth <christoph@vieth.me>    
 * @license MIT License http://opensource.org/licenses/MIT
 * @url http://www.falkens-laboratory.de/2015/01/shopify-checkout-hack.html
 */
 
(function() {
    var checkReady = function(callback) {
        if (window.jQuery) {
            callback(jQuery);
        } else {
            window.setTimeout(function() {
                checkReady(callback);
            }, 100);
        }
    };
    var runCode = function($) {
        var checkoutPage = $('#checkout');
        if (checkoutPage.length > 0) {
            if (checkoutPage.hasClass(
                    'current-step-contact_information')) {
                /**
                 * Contact Information Step
                 */
                 
                /* Add Code here */
            } else if (checkoutPage.hasClass(
                    'current-step-shipping_and_payment_method')) {
                /**
                 * Shipping and Payment Step
                 */
                 
                /* Add Code here */
            } else if (checkoutPage.hasClass('current-step-review')) {
                /**
                 * Review Page Step
                 */
                 
                /* Add Code here */
            }
        }
    };
    if (typeof jQuery == "undefined") {
        var script = document.createElement("SCRIPT");
        script.src =
            'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js';
        script.type = 'text/javascript';
        document.getElementsByTagName("head")[0].appendChild(script);
        checkReady(function($) {
            runCode($);
        });
    } else {
        runCode(jQuery);
    }
})();