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# type-is
[![NPM Version][npm-version-image]][npm-url] [![NPM Downloads][npm-downloads-image]][npm-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') }) ```
### 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:
<!-- 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) { // ... }) } ```
### 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](https://tools.ietf.org/html/rfc6838) 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:
<!-- 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 ```
## 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)
[coveralls-image]: https://badgen.net/coveralls/c/github/jshttp/type-is/master [coveralls-url]: https://coveralls.io/r/jshttp/type-is?branch=master [node-version-image]: https://badgen.net/npm/node/type-is [node-version-url]: https://nodejs.org/en/download [npm-downloads-image]: https://badgen.net/npm/dm/type-is [npm-url]: https://npmjs.org/package/type-is [npm-version-image]: https://badgen.net/npm/v/type-is [travis-image]: https://badgen.net/travis/jshttp/type-is/master [travis-url]: https://travis-ci.org/jshttp/type-is
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