In a very simple language middleware are like a guard or we can say that they are like a ticket checker in a train.
That are placed just before any website's route handler or we can say end points of a website.
For example - In a website what kind of routs or end points can be there which are common
1.) Sign up
2.) Password
These two end points are very common which are present in almost every website.
Before any user enters their details to these routs or end points.
They are passed to the middleware where they check that the information entered are as expected or not.
If not then the user is not allowed to enter and vice-versa.
Middleware functions have the access to three inputs they are as follows
1.) req [request object]
2.) res [response object]
3.) next [which calls the next function]
Here is an example
- Output
- This an example that how a middleware works.