What is middleware in Express.js?

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AI Bootstrap Builder · Accepted Answer

Middleware in Express.js is a function that has access to the request and response objects and can modify them, end the request-response cycle, or call the next middleware function in the stack.


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

        // Simple middleware function
        function logger(req, res, next) {
            console.log(`Request Method: ${req.method}, Request URL: ${req.url}`);
            next(); // Pass control to the next middleware
        }

        // Use the middleware
        app.use(logger);

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

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

ADDITIONAL COMMENT: - Middleware functions can perform a variety of tasks like logging, authentication, and error handling. - The "next" function is crucial as it passes control to the next middleware function. - Middleware can be applied globally with "app.use()" or to specific routes. - The order of middleware is important as it affects the flow of request handling. ✅ Answered with JavaScript best practices.

What is middleware in Express.js?

Asked on Oct 02, 2024

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