What is the correct way to “end” a request from express/connect middleware?

问题

Assuming I have middleware such as this;

var express = require('express');
var app = express();

app.use(function (req, res, next) {
    var host = "example.com";

    if (req.host !== host) {
        res.redirect(301, host + req.originalUrl);
        res.end();
    }
});

What sort of rules do I need to abide by here?

1. Should I be calling res.end()? (or does res.redirect() do this for me?)
2. Should I be calling next()? (or does connect detect the request has ended and exit cleanly?)
3. Assuming that I should be calling next(), I guess that means I can potentially be receiving requests to my middleware which may have already been ended by other middleware higher in the chain; how do I protect myself against this?

回答1:

1. res.redirect() indeed calls res.end() itself;
2. You should call next() if your middleware isn't the end point; in the case of generating a redirect, it is an endpoint and next() shouldn't be called, but if req.host === host, you need to call next() to move the request up the chain to other middleware/routes;
3. A request doesn't get ended, a response does. And when it does, it will end the middleware chain so you don't have to worry about it.

来源：https://stackoverflow.com/questions/15571779/what-is-the-correct-way-to-end-a-request-from-express-connect-middleware