accepts

Higher-level content negotiation

accepts

Higher level content negotiation based on negotiator. Extracted from koa for general use.

In addition to negotiator, it allows:

  • Allows types as an array or arguments list, ie (['text/html', 'application/json']) as well as ('text/html', 'application/json').
  • Allows type shorthands such as json.
  • Returns false when no types match
  • Treats non-existent headers as *
npm install accepts
var accepts = require('accepts')

Create a new Accepts object for the given req.

Return the first accepted charset. If nothing in charsets is accepted, then false is returned.

Return the charsets that the request accepts, in the order of the client's preference (most preferred first).

Return the first accepted encoding. If nothing in encodings is accepted, then false is returned.

Return the encodings that the request accepts, in the order of the client's preference (most preferred first).

Return the first accepted language. If nothing in languages is accepted, then false is returned.

Return the languages that the request accepts, in the order of the client's preference (most preferred first).

Return the first accepted type (and it is returned as the same text as what appears in the types array). If nothing in types is accepted, then false is returned.

The types array can contain full MIME types or file extensions. Any value that is not a full MIME types is passed to require('mime-types').lookup.

Return the types that the request accepts, in the order of the client's preference (most preferred first).

This simple example shows how to use accepts to return a different typed respond body based on what the client wants to accept. The server lists it's preferences in order and will get back the best match between the client and server.

var accepts = require('accepts')
var http = require('http')
 
function app(reqres) {
  var accept = accepts(req)
 
  // the order of this list is significant; should be server preferred order 
  switch(accept.type(['json', 'html'])) {
    case 'json':
      res.setHeader('Content-Type', 'application/json')
      res.write('{"hello":"world!"}')
      break
    case 'html':
      res.setHeader('Content-Type', 'text/html')
      res.write('<b>hello, world!</b>')
      break
    default:
      // the fallback is text/plain, so no need to specify it above 
      res.setHeader('Content-Type', 'text/plain')
      res.write('hello, world!')
      break
  }
 
  res.end()
}
 
http.createServer(app).listen(3000)

You can test this out with the cURL program:

curl -I -H'Accept: text/html' http://localhost:3000/

MIT