修复了促销信息只有一条时的js bug --code reviewed by zhaobiao

@@ -52,13 +52,13 @@ goodsSwiper = new Swiper('.banner-swiper', {
 
 
 //初始化goods-discount
-if (0 === $('.goodsDiscount .discount-folder').children().length) {
+if (0 === $discountFolder.children().length) {
     $discountFolder.css('display', 'none');
     $discountArrow.html('');
 }
 
 //goods-discount下拉按钮点击事件
-if (goodsDiscountHammer) {
+if (goodsDiscountHammer && $discountFolder.children().length > 0) {
     goodsDiscountHammer.on('tap', function(e) {
         if ($discountFolder.is(':hidden')) {
             $discountArrow.removeClass('icon-down').addClass('icon-up').html('');
@@ -67,7 +67,6 @@ if (goodsDiscountHammer) {
             $discountArrow.removeClass('icon-up').addClass('icon-down').html('');
             $discountFolder.slideUp();
         }
-        return false;
     });
 }