|Middleware| Middleware: The Key to Express

#javascript #html #css #webdev

-Intro to Express Middleware
-Using Morgan - Logger Middleware
-Defining Our Own Middleware
-Setting Up a 404 Route

Intro to Express Middleware

Middleware are functions that run at some point during the request and response lifecycle. The functions run between the time a request enters express and by the time the response leaves and the code stops executing. Each middleware function has access to the request object into the response object.
Middleware can end the HTTP request by sending back a response with methods like res.send() or middleware can be chained together one after another

The main job of the middleware is to parse the incoming body of the request and add it to the request object.

Using Morgan - Logger Middleware

https://github.com/expressjs/morgan

Morgan - is a simple logger that helps log HTTP requests information to our terminal. Very useful when debugging things.

Defining Our Own Middleware


app.use(morgan('common'))
app.use((req, res, next) => {
 console.log('This is the first middleware!')
 next(); 
})


app.use(morgan('common'))
app.use((req, res, next) => {
 console.log('This is the second middleware!')
 next(); 
})

the next() statement is there to keep the code moving forward, otherwise the code would end after the console.log statement.

Setting Up a 404 Route


app.use((req, res, next) => {
  req.requestTime = Date.now(); 
  console.log(req.method, req.path); 
  next(); 
}) 

app.use((req, res) => {
 res.status.(404).send('Not Found')
})