if (req.header.authorization) {
 // do soemthing
} else {
var cookieValues = req.cookies["demo"]
}

WWW-Authenticate: Basic realm="your server"

Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==

var express = require('express');
var morgan = require('morgan');
var cookieParser = require('cookie-parser');


var hostname = 'localhost';
var port = 3000;

var app = express();

app.use(morgan('dev'));


app.use(cookieParser('12345-67890-09876-54321')); // secret key


function auth( req, res, next){
    if (!req.signedCookies.user){//如果user不存在
    console.log(req.headers);
    var authHeader = req.headers.authorization;//获取认证情况的集合
    if(!authHeader){
        var err = new Error("you could not be authorized");
        err.status = 401;
        next(err);
        return;
    }
    console.log('authHeader :'+authHeader);
//cookie 里名称，密码形式为： user: password
    var auth = new Buffer(authHeader.split(' ')[1], 'base64').toString().split(':');
    var user = auth[0];
    var pass = auth[1];
    if (user == 'admin' && pass =='password') {
        res.cookie('user', 'admin', {signed: true});

        next();
    }else{
        var err = new Error("you could not be authorized");
        err.status = 401;
        next(err);

    }
}
    else {
        if (req.signedCookies.user == 'admin') {
            next();
        }else{
        var err = new Error("you could not be authorized");
        err.status = 401;
        next(err);
        }
    }


}


app.use(auth);

app.use(express.static(__dirname+'/public'));
app.use(function(err, req, res, next){
    res.writeHead(err.status || 500,
     {'WWW-Authenticate':'Basic',
     'Content-Type':'text/plain'
 });
    res.end(err.message);
});

// print
app.listen(port, hostname, function(){
    console.log('Server running at :'+hostname+ ': '+port);
});