Express下大概无难点，但是有几个小点需要记一下，算是技巧：

1. 结局跨域等的问题，需要在主文件一进来做如下策略，网络上很容易找到，这里就不贴具体出处了：

    app.all('*', function (req, res, next) {
        res.header("Access-Control-Allow-Origin", "http://localhost:4200"); // 允许所有就写*
        res.header('Access-Control-Allow-Credentials',true); // 这句解决跨域引起session丢失，客户端也要做策略
        res.header('Access-Control-Allow-Methods', 'GET'); // 允许的请求方法
        res.header('Access-Control-Allow-Methods', 'POST');
        res.header("Access-Control-Allow-Headers", "X-Requested-With, Content-Type"); // 允许的头字段
        next();
    });

2. 路由分级策略

**在app.js中**

    require('./routes/routemgr')(app);

**在routemgr.js中**

    var express = require('express');
    var router = express.Router();
    module.exports = function(app){
        app.get('/', function(req, res, next){
            res.json("root");
        });
        app.use('/login', require('./login'));
        app.use('/others', require('./others'));
    };

**然后在每个相应的文件中**

    var express = require('express');
    var router = express.Router();

    router.get('/', function (req, res, next) {
        res.json("login root");
    });

3. 静态配置文件需要这么写

module.exports = {
    mysql: {
        host: '127.0.0.1',
        port: 3306,
        user: 'root',
        password: 'root',
        database: 'db_test',
        charset: 'utf8'
    },
    session: function(MongoStore){
        return {
            resave:false,//添加这行，重新保存：强制会话保存即使是未修改的；
            saveUninitialized: true,//添加这行 ，强制“未初始化的”会话保存到存储
            key: "session~",//cookie name
            cookie: {
                path: '/',
                httpOnly: true,
                secure: false, // TODO: Set to true when HTTPS was used.
                maxAge: 1000 * 60 * 60 * 24 * 30

            },
            secret: "qwerasdf",
            store: new MongoStore({
                db: "db_session"
            })
        }
    }
};