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 function?

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 apply multiple middleware functions?

You can apply multiple middleware functions by calling app.use() multiple times. For example:

app.use(middleware1);
app.use(middleware2);

They will be executed in the order they are defined.

What if I want to use middleware for specific routes?

You can specify middleware for specific routes by passing the route as the first argument:

app.get('/specific-route', middlewareFunction, (req, res) => {
    res.send('This route uses specific middleware!');
});