type-is

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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')
})

typeis(request, types)

Checks if the request is one of the types. If the request has no body, even if there is a Content-Type header, then null is returned. If the Content-Type header is invalid or does not matches any of the types, then false is returned. Otherwise, a string of the type that matched is returned.

The request argument is expected to be a Node.js HTTP request. The types argument is an array of type strings.

Each type in the types array can be one of the following:

- A file 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.

Some examples to illustrate the inputs and returned value:

// 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) {
    // ...
  })
}

typeis.is(mediaType, types)

Checks if the mediaType is one of the types. If the mediaType is invalid or does not matches any of the types, then false is returned. Otherwise, a string of the type that matched is returned.

The mediaType argument is expected to be a media type string. The types argument is an array of type strings.

Each type in the types array can be one of the following:

- A file 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.

Some examples to illustrate the inputs and returned value:

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

typeis.match(expected, actual)

Match the type string expected with actual, taking in to account wildcards. A wildcard can only be in the type of the subtype part of a media type and only in the expected value (as actual should be the real media type to match). A suffix can still be included even with a wildcard subtype. If an input is malformed, false will be returned.

typeis.match('text/html', 'text/html') // => true
typeis.match('*/html', 'text/html') // => true
typeis.match('text/*', 'text/html') // => true
typeis.match('/', 'text/html') // => true
typeis.match('/+json', 'application/x-custom+json') // => true

typeis.normalize(type)

Normalize a type string. This works by performing the following:

- If the type is not a string, false is returned.

If the string starts with + (so it is a +suffix shorthand like +json),

then it is expanded to contain the complete wildcard notation of /+suffix.

If the string contains a /, then it is returned as the type.
Else the string is assumed to be a file extension and the mapped media type is

returned, or false is there is no mapping.

This includes two special mappings:

- 'multipart' -> 'multipart/*'

'urlencoded' -> 'application/x-www-form-urlencoded'
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

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📄 README.md