toLowerCase（）函数与passport.js身份验证

Question

我正在研究＆＃34;注册＆＃34;我的网络应用程序的路由。在我的路由中，我使用toLowerCase（）函数将用户输入的用户名转换为小写，但这会导致passport.authenticate（）方法失败（用户仍然完全注册）并重定向到Unauthorized（401）响应。当我尝试不使用toLowerCase（）函数时，它工作得很好。不知道我在这里缺少什么，所以任何帮助将不胜感激！

router.post("/register", isLoggedOut, function(req,res){
var username = req.body.username;
var password = req.body.password;
var confirm_password = req.body.confirm_password;
for (var i = 0; i < emails.length; i++){
    if (username.toLowerCase() == emails[i].toLowerCase()){
        username = username.toLowerCase(); 
        if (password != confirm_password){
            req.flash("error", "Passwords do not match!");
            return res.redirect("/register");
        } else {
            console.log("Password matches! Signing up now");
            console.log("Type of username is " + typeof req.body.username);
            console.log("Type of username after lowercase: " + typeof req.body.username.toLowerCase());
            var newUser = new User({username: username, role: "public"});
            User.register(newUser, req.body.password, function(err, user){
                if (err){
                    console.log("There is an error in registration: " + err);
                    req.flash("error", err.message);
                    return res.redirect("/register");
                }
                passport.authenticate("local")(req, res, function(err){
                    if (err){
                        console.log("ERROR IN AUTHENTICATE!: " + err);
                    }
                    req.flash("success", "Welcome");
                    return res.redirect("/blogs");
                });
            });
        }
    }
    else {
        if (i == emails.length - 1){
            console.log("Email is not in system");
            req.flash("error", "Your email is not in our system!");
            return res.redirect("/register");
        } 
    }
}

}）;