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# type-is
[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Node.js Version][node-version-image]][node-version-url]
[![Build Status][travis-image]][travis-url]
[![Test Coverage][coveralls-image]][coveralls-url]
Infer the content-type of a request.
### Install
This is a [Node.js](https://nodejs.org/en/) module available through the
[npm registry](https://www.npmjs.com/). Installation is done using the
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
```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')
})
```
### type = typeis(request, types)
`request` is the node HTTP request. `types` is an array of types.
<!-- eslint-disable no-undef -->
```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
```
### 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.
<!-- eslint-disable no-undef -->
```js
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](https://tools.ietf.org/html/rfc6838) string. `types` is an array of types.
<!-- eslint-disable no-undef -->
```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
```
### 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
```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](LICENSE)
[npm-image]: https://img.shields.io/npm/v/type-is.svg
[npm-url]: https://npmjs.org/package/type-is
[node-version-image]: https://img.shields.io/node/v/type-is.svg
[node-version-url]: https://nodejs.org/en/download/
[travis-image]: https://img.shields.io/travis/jshttp/type-is/master.svg
[travis-url]: https://travis-ci.org/jshttp/type-is
[coveralls-image]: https://img.shields.io/coveralls/jshttp/type-is/master.svg
[coveralls-url]: https://coveralls.io/r/jshttp/type-is?branch=master
[downloads-image]: https://img.shields.io/npm/dm/type-is.svg
[downloads-url]: https://npmjs.org/package/type-is
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