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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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