express官网里的例子如何理解？

Question

// invoked for any requests passed to this router
router.use(function(req, res, next) {
  // .. some logic here .. like any other middleware
  next();
});

// will handle any request that ends in /events
// depends on where the router is "use()'d"
router.get('/events', function(req, res, next) {
  // ..
});

You can then use a router for a particular root URL in this way separating your routes into files or even mini-apps.

// only requests to /calendar/* will be sent to our "router"
app.use('/calendar', router);

阅读上面代码有一些问题请教：
1.router.get('/events', function(req, res, next) {}); 是将函数映射到/events上，
而app.use('/calendar', router);是将中间件挂载到/calendar上。如果监听的3100端口，我们在浏览器中输入的http://127.0.0.1:3100/calendar，这是不会执行router.get('/events',function(){})中的函数的。上面说的You can then use a router for a particular root URL in this way separating your routes into files or even mini-apps.s这句话该怎么理解？particular root URL是什么？

Answer 1

这个是get请求发送过来后，use可以接受所有类型的请求，然后将数据带到下一个路由get中，其实use和get这两个路由都会走一遍，next就是自动执行下一个路由，链式反应