...
function processSignup(req,res){
   var newUser = new User({
      email: req.body.email,
      name: req.body.name,
      password: req.body.password,
   });
   bcrypt.hash(newUser.password , 10 ,function(err,hash){
      if(err) throw err;
      newUser.password = hash;
      newUser.save()
         .then(() => {
            req.flash("success", "Bạn đã đăng kí account success !!!");
            res.redirect("login");
         }
         )
         .catch(err => res.send(err))
   })
}

function showLogin(req,res){
   res.render("user/login" , {
      success: req.flash("success")
   })
}