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:

``sh
$ npm install type-is
`

API

`js
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')
})
`

$3

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:

`js
// 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
`

$3

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.

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

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

$3

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:

`js
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
`

$3

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.

`js
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
`

$3

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

$3

`js
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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