Express app.use() Function Last Updated : 12 Apr, 2025 Summarize Comments Improve Suggest changes Share Like Article Like Report The app.use() function in Express.js adds middleware to the application's request-processing pipeline. It applies the specified middleware to all incoming requests or to specific routes, allowing you to modify request/response objects, perform operations, or handle errors throughout the application.Syntaxapp.use(path, callback)Parameters:path: It is the path for which the middleware function is being called. It can be a string representing a path or path pattern or a regular expression pattern to match the paths.callback: It is a middleware function or a series/array of middleware functions.Steps to create the application:Step 1: You can install this package by using this command.npm install expressStep 2: After installing the express module, you can check your express version in the command prompt using the command.npm version expressProject Structure:The updated dependencies in package.json file will look like:"dependencies": { "express": "^5.1.0",} Example: Below is the code example of middleware. JavaScript const express = require('express'); const app = express(); const PORT = 3000; // This middleware will log the request and // allow it to proceed to the next handler app.use(function (req, res, next) { console.log("Middleware called"); next(); }); // Requests will reach this route after // passing through the middleware app.get('/user', function (req, res) { console.log("/user request called"); res.send('Welcome to GeeksforGeeks'); }); app.listen(PORT, function (err) { if (err) console.log(err); console.log(`Server listening on PORT ${PORT}`); }); Steps to run the program:node index.jsConsole Output:OutputBrowser Output: Now open your browser and go to http://localhost:3000/user and you can seeOutputWe have a complete list of Express Application module methods, properties and events, to check those please go through this Express.js Application Complete Reference article. Comment More infoAdvertise with us Next Article Express app.use() Function G gouravhammad Follow Improve Article Tags : JavaScript Web Technologies Node.js Express.js Similar Reads JavaScript Tutorial JavaScript is a programming language used to create dynamic content for websites. It is a lightweight, cross-platform, and single-threaded programming language. It's an interpreted language that executes code line by line, providing more flexibility.JavaScript on Client Side: On the client side, Jav 11 min read Web Development Web development is the process of creating, building, and maintaining websites and web applications. It involves everything from web design to programming and database management. Web development is generally divided into three core areas: Frontend Development, Backend Development, and Full Stack De 5 min read React Interview Questions and Answers React is an efficient, flexible, and open-source JavaScript library that allows developers to create simple, fast, and scalable web applications. Jordan Walke, a software engineer who was working for Facebook, created React. Developers with a JavaScript background can easily develop web applications 15+ min read React Tutorial React is a powerful JavaScript library for building fast, scalable front-end applications. Created by Facebook, it's known for its component-based structure, single-page applications (SPAs), and virtual DOM,enabling efficient UI updates and a seamless user experience.Note: The latest stable version 7 min read JavaScript Interview Questions and Answers JavaScript is the most used programming language for developing websites, web servers, mobile applications, and many other platforms. In Both Front-end and Back-end Interviews, JavaScript was asked, and its difficulty depends upon the on your profile and company. Here, we compiled 70+ JS Interview q 15+ min read REST API Introduction REST API stands for REpresentational State Transfer API. It is a type of API (Application Programming Interface) that allows communication between different systems over the internet. REST APIs work by sending requests and receiving responses, typically in JSON format, between the client and server. 7 min read Domain Name System (DNS) DNS is a hierarchical and distributed naming system that translates domain names into IP addresses. When you type a domain name like www.geeksforgeeks.org into your browser, DNS ensures that the request reaches the correct server by resolving the domain to its corresponding IP address.Without DNS, w 8 min read HTML Interview Questions and Answers HTML (HyperText Markup Language) is the foundational language for creating web pages and web applications. Whether you're a fresher or an experienced professional, preparing for an HTML interview requires a solid understanding of both basic and advanced concepts. Below is a curated list of 50+ HTML 14 min read NodeJS Interview Questions and Answers NodeJS is one of the most popular runtime environments, known for its efficiency, scalability, and ability to handle asynchronous operations. It is built on Chromeâs V8 JavaScript engine for executing JavaScript code outside of a browser. It is extensively used by top companies such as LinkedIn, Net 15+ min read Web Development Technologies Web development refers to building, creating, and maintaining websites. It includes aspects such as web design, web publishing, web programming, and database management. It is the creation of an application that works over the internet, i.e., websites.To better understand the foundation of web devel 7 min read Like