type-is

Infer the content-type of a request.

Install

This is a Node.js module available through the npm registry. Installation is done using the npm install command:

$ npm install type-is

API

var http = require('http')
var typeis = require('type-is')

http.createServer(function (req, res) {
  var istext = typeis(req, ['text/*'])
  res.end('you ' + (istext ? 'sent' : 'did not send') + ' me text')
})

type = typeis(request, types)

request is the node HTTP request. types is an array of types.

// req.headers.content-type = 'application/json'

typeis(req, ['json'])             // 'json'
typeis(req, ['html', 'json'])     // 'json'
typeis(req, ['application/*'])    // 'application/json'
typeis(req, ['application/json']) // 'application/json'

typeis(req, ['html']) // false

typeis.hasBody(request)

Returns a Boolean if the given request has a body, regardless of the Content-Type header.

Having a body has no relation to how large the body is (it may be 0 bytes). This is similar to how file existence works. If a body does exist, then this indicates that there is data to read from the Node.js request stream.

if (typeis.hasBody(req)) {
  // read the body, since there is one

  req.on('data', function (chunk) {
    // ...
  })
}

type = typeis.is(mediaType, types)

mediaType is the media type string. types is an array of types.

var mediaType = 'application/json'

typeis.is(mediaType, ['json'])             // 'json'
typeis.is(mediaType, ['html', 'json'])     // 'json'
typeis.is(mediaType, ['application/*'])    // 'application/json'
typeis.is(mediaType, ['application/json']) // 'application/json'

typeis.is(mediaType, ['html']) // false

Each type can be:

• An extension name such as json. This name will be returned if matched.
• A mime type such as application/json.
• A mime type with a wildcard such as */* or */json or application/*. The full mime type will be returned if matched.
• A suffix such as +json. This can be combined with a wildcard such as */vnd+json or application/*+json. The full mime type will be returned if matched.

false will be returned if no type matches or the content type is invalid.

null will be returned if the request does not have a body.

Examples

Example body parser

var express = require('express')
var typeis = require('type-is')

var app = express()

app.use(function bodyParser (req, res, next) {
  if (!typeis.hasBody(req)) {
    return next()
  }

  switch (typeis(req, ['urlencoded', 'json', 'multipart'])) {
    case 'urlencoded':
      // parse urlencoded body
      throw new Error('implement urlencoded body parsing')
    case 'json':
      // parse json body
      throw new Error('implement json body parsing')
    case 'multipart':
      // parse multipart body
      throw new Error('implement multipart body parsing')
    default:
      // 415 error code
      res.statusCode = 415
      res.end()
      break
  }
})

License

MIT