How can I log errors in middleware effectively?

How can I log errors in middleware effectively?

You can log errors in middleware by using a logging library like Winston or Morgan. Would you like a code example?

Yes, please provide a code example using Express.js.

Sure! Here's a simple example:

const express = require('express');
const logger = require('winston');

const app = express();

app.use((err, req, res, next) => {
    logger.error(err.stack);
    res.status(500).send('Something broke!');
});

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

This middleware logs the error stack and sends a response.

What if I want to log errors to a file instead of the console?

You can configure Winston to log to a file by adding a file transport. Here's how:

const winston = require('winston');

const logger = winston.createLogger({
    transports: [
        new winston.transports.File({ filename: 'error.log' })
    ]
});

This will log errors to 'error.log'.