Wie kann ich AJAX-gesteuerte Website-Interaktionen effektiv automatisieren?

// ==UserScript==
// @name     Nike Auto-Buy Shoes
// @include  http*://store.nike.com/*
// @require  http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js
// @require  https://gist.github.com/raw/2625891/waitForKeyElements.js
// @grant    GM_addStyle
// ==/UserScript==

var targetShoeSize = "10";

//-- Step 1: Activate Size Dropdown
waitForKeyElements(
  "div.footwear form.add-to-cart-form span.sizeDropdown a.size-dropdown",
  activateSizeDropdown
);

function activateSizeDropdown(jNode) {
  triggerMouseEvent(jNode[0], "mousedown");

  //-- Setup Step 2
  waitForKeyElements(
    "ul.selectBox-dropdown-menu li a:contains('" + targetShoeSize + "'):visible",
    selectDesiredShoeSize
  );
}

//-- Step 2: Select Target Shoe Size
function selectDesiredShoeSize(jNode) {
  if ($.trim(jNode.text()) === targetShoeSize) {
    //-- Trigger triplex event
    triggerMouseEvent(jNode[0], "mouseover");
    triggerMouseEvent(jNode[0], "mousedown");
    triggerMouseEvent(jNode[0], "mouseup");

    //-- Setup Steps 3 and 4
    waitForKeyElements(
      "div.footwear form.add-to-cart-form span.sizeDropdown a.selectBox span.selectBox-label:contains('(" + targetShoeSize + ")')",
      waitForShoeSizeDisplayAndAddToCart
    );
  }
}

//-- Steps 3 and 4: Wait for Shoe Size Display and Add to Cart
function waitForShoeSizeDisplayAndAddToCart(jNode) {
  var addToCartButton = $(
    "div.footwear form.add-to-cart-form div.product-selections div.add-to-cart"
  );
  triggerMouseEvent(addToCartButton[0], "click");

  //-- Setup Step 5
  waitForKeyElements(
    "div.mini-cart div.cart-item-data a.checkout-button:visible",
    clickTheCheckoutButton
  );
}

//-- Step 5: Click the Checkout Button
function clickTheCheckoutButton(jNode) {
  triggerMouseEvent(jNode[0], "click");
}

function triggerMouseEvent(node, eventType) {
  var clickEvent = document.createEvent("MouseEvents");
  clickEvent.initEvent(eventType, true, true);
  node.dispatchEvent(clickEvent);
}