refactor

@@ -70,11 +70,7 @@ function doPassportCallback(req, res, user) {
 
 const common = {
     beforeLogin: (req, res, next) => {
-        let refer = req.query.refer;
-
-        if (!refer) {
-            refer = req.get('Referer');
-        }
+        let refer = req.query.refer || req.get('Referer');
 
         refer && res.cookie('refer', encodeURI(refer), {
             domain: 'yohobuy.com'