merge detail page update. code review by XWG

@@ -12,13 +12,17 @@ var goodsSwiper,
     $discountFolder = $('.goodsDiscount .discount-folder'),
     $discountArrow = $('.goodsDiscount .first-item span');
 
-var goodsDiscountHammer = new Hammer(document.getElementById('goodsDiscount'));
+var goodsDiscountEl = document.getElementById('goodsDiscount'),
+    goodsDiscountHammer = goodsDiscountEl && new Hammer(goodsDiscountEl);
 
 require('./desc');
 require('./comments-consults');
 
 //add extra marign-bottom for footer to show the yoho copyright
-window.reMarginFooter('.cart-bar');
+
+function showFooter() {
+    window.reMarginFooter('.cart-bar');
+}
 
 lazyLoad($('img.lazy'));
 
@@ -40,7 +44,8 @@ if (0 === $('.goodsDiscount .discount-folder').children().length) {
 }
 
 //goods-discount下拉按钮点击事件
-goodsDiscountHammer.on('tap', function(e) {
+if (goodsDiscountHammer) {
+    goodsDiscountHammer.on('tap', function(e) {
         if ($discountFolder.is(':hidden')) {
             $discountArrow.removeClass('icon-down').addClass('icon-up').html('');
             $discountFolder.slideDown();
@@ -49,6 +54,9 @@ goodsDiscountHammer.on('tap', function(e) {
             $discountFolder.slideUp();
         }
         return false;
-});
+    });
+}
 
 require('./like');
+
+$(document).ready(showFooter);