I am using Passport on my node.js app and I am currently using an Username to login.

On my user register page, I have allow the user to register their unique username and Email.

I want a login page with "Sign in Using username/email:" ________

Where the script can detect if there is a "@" in the field and look up the email instead of username.

I have tried for a few hours with no avail.

here is my passport.js

var mongoose = require('mongoose')
var LocalStrategy = require('passport-local').Strategy

var User = mongoose.model('User');

module.exports = function(passport, config){

passport.serializeUser(function(user, done){
    done(null, user.id);
})

passport.deserializeUser(function(id, done) {
    User.findOne({ _id: id }, function (err, user) {
        done(err, user);
    });
});

passport.use(new LocalStrategy({
    usernameField: 'username',
    passwordField: 'password'
    }, function(username, password, done) {
    User.isValidUserPassword(username, password, done);
    }));
}

EDIT: below is the user.js as requested

var mongoose = require('mongoose');
var hash = require('../util/hash.js');

UserSchema = mongoose.Schema({
username:  String,
email:      String,
salt:       String,
hash:       String
})

UserSchema.statics.signup = function(username, email, password, done){
var User = this;

hash(password, function(err, salt, hash){
    if(err) throw err;
    // if (err) return done(err);
    User.create({
        username : username,
        email: email,
        salt : salt,
        hash : hash
    }, function(err, user){
        if(err) throw err;
        // if (err) return done(err);
        done(null, user);
    });
});
}

UserSchema.statics.isValidUserPassword = function(username, password, done) {
this.findOne({username : username}, function(err, user){
    // if(err) throw err;
    if(err) return done(err);
    if(!user) return done(null, false, { message : 'Incorrect username.' });
    hash(password, user.salt, function(err, hash){
        if(err) return done(err);
        if(hash == user.hash) return done(null, user);
        done(null, false, {
            message : 'Incorrect password'
        });
    });
});
};

var User = mongoose.model("User", UserSchema);

module.exports = User;

Ok, you should have something like this in your Mongoose model:

UserSchema.statics.isValidUserPassword = function(username, password, done) {
    var criteria = (username.indexOf('@') === -1) ? {username: username} : {email: username};
    this.findOne(criteria, function(err, user){
        // All the same...
    });
};