Express

Express.js is a minimal web framework for Node.js. It handles routing (mapping URLs to handler functions), middleware (functions that run on every request), and sending responses. It works with any frontend: React, Vue, or plain HTML.

Express is one of the most widely used Node.js frameworks. It does not impose a fixed project structure, so you can organise your code however makes sense for your project.

Express 5

Express 5 was released in 2024. All examples in this guide work on Express 5. The main change from Express 4 is that async route handlers now propagate thrown errors automatically, so you no longer need to wrap every async handler in a try/catch and call next(err) manually.

Install Express with:

npm install express

What to know first

Before starting with Express, you should be comfortable with:

• JavaScript fundamentals : variables, functions, objects, arrays
• Arrow functions
• Async/await and Promises
• HTTP basics: methods (GET, POST, PUT, DELETE), status codes, headers
• JSON: reading and writing JSON data

Pages in this section

• Installation : set up an Express project and configure nodemon
• Creating an Express App : the basic server structure and hello world
• Routing : GET, POST, PUT, DELETE, route parameters, and query strings
• Request Object : reading params, query strings, body, and headers
• Response Object : sending text, JSON, files, and redirects
• Middleware : custom middleware, built-in middleware, and third-party packages
• express.Router() : splitting routes into separate files
• Serve Static Files : serving HTML, CSS, and images with express.static
• View Engines : rendering dynamic HTML with EJS

What to read next

• Installation : get your first Express app running