Access HTTP headers values from a request

You can access all the HTTP headers using the Request.headers property:

app.get('/', (req, res) => {
  console.log(req.headers)
})

Use the Request.header() method to access one individual request header value:

app.get('/', (req, res) => {
  req.header('User-Agent')
})

Change any HTTP header value of a response

You can change any HTTP header value using Response.set():

res.set('Content-Type', 'text/html')

There is a shortcut for the Content-Type header however:

res.type('.html')
// => 'text/html'

res.type('html')
// => 'text/html'

res.type('json')
// => 'application/json'

res.type('application/json')
// => 'application/json'

res.type('png')
// => image/png: