Writing configurable middleware functions

A common pattern for writing middleware functions is to wrap the middleware function inside another function. The result of doing so is a configurable middleware function. They are also higher-order functions, that is, a function that returns another function.

const fn = (options) => (response, request, next) => {  
    next()  
} 

Usually an object is used as an options parameters. However, there is nothing stopping you from doing it in your own way.

Getting ready

In this recipe, you will write a configurable logger middleware function. Before you start, create a new package.json file with the following content:

{ 
    "dependencies": { 
        "express": "4.16.3" 
    } 
} 

Then, install the dependencies by opening a terminal and running:

npm install

How to do it...

What your configurable middleware function will do is simple: it will print the status code and the URL when a request is made.

1. Create a new file named middleware-logger.js

2. Export a function...