How do I use middleware in Express.js?

How do I use middleware in Express.js?

Middleware in Express.js are functions that have access to the request, response, and next middleware function. You can use them to modify the request and response objects, end the request-response cycle, or call the next middleware in the stack.

Can you give me an example of a simple middleware?

Sure! Here's a simple logging middleware:

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

This logs the HTTP method and URL of each request.

How do I handle errors with middleware?

You can create an error-handling middleware by defining a function with four parameters: err, req, res, and next. Here's an example:

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