How can I implement logging middleware in Express.js?

How can I implement logging middleware in Express.js?

You can create a logging middleware function that logs requests and responses. Would you like a code example?

Yes, please provide a code example.

Here's a simple example:

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

const logger = (req, res, next) => {
    console.log(`${req.method} ${req.url}`);
    next();
};

app.use(logger);

app.get('/', (req, res) => {
    res.send('Hello World!');
});

app.listen(3000, () => {
    console.log('Server is running on port 3000');
});

This middleware logs the HTTP method and URL of each request.

How can I log additional information like response time?

You can use the Date object to calculate the response time. Here's an updated example:

const logger = (req, res, next) => {
    const start = Date.now();
    res.on('finish', () => {
        const duration = Date.now() - start;
        console.log(`${req.method} ${req.url} - ${duration}ms`);
    });
    next();
};