Middleware functions are functions that have access to the request object (req), the response object (res), and the next middleware function in the application’s request-response cycle
Middleware functions can perform the following tasks:
Execute any code.
Make changes to the request and the response objects.
End the request-response cycle.
Call the next middleware function in the stack
An Express application is essentially a series of middleware function calls
Here’s an example of one type of Middleware that can be found in an Express application
app.get('/user/:id', function (req, res, next) {
res.send('USER')
})
.get() middleware to listen for GET requests to /user/:id