弹窗优化

@@ -88,6 +88,8 @@ function Dialog(options) {
 Dialog.prototype.close = function() {
     this.$mask && this.$mask.addClass('hide');
     this.$el.remove();
+    
+    return this;
 };
 
 Dialog.prototype.show = function() {
@@ -96,6 +98,8 @@ Dialog.prototype.show = function() {
         'margin-top': -this.$el.outerHeight() / 2,
         'margin-left': -this.$el.outerWidth() / 2
     });
+
+    return this;
 };
 
 exports.Dialog = Dialog;