购物车没有tab时 不能结算

@@ -19,8 +19,9 @@ require('./good');
 
 lazyLoad($('img.lazy'));
 
-navHammer = new Hammer(document.getElementsByClassName('cart-nav')[0]);
-navHammer.on('tap', function(e) {
+if ($('.cart-nav').length > 0) {
+    navHammer = new Hammer(document.getElementsByClassName('cart-nav')[0]);
+    navHammer.on('tap', function(e) {
         var $this = $(e.target).closest('li');
 
         if ($this.hasClass('active')) {
@@ -41,7 +42,8 @@ navHammer.on('tap', function(e) {
 
         //trigger lazyload
         $(window).trigger('scroll');
-});
+    });
+}
 
 $('.btn-balance').on('touchend', function() {
     window.location.href = '/cart/index/orderEnsure?cartType=' + cartType;