171 lines
5.1 KiB
Markdown
171 lines
5.1 KiB
Markdown
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# type-is
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[![NPM Version][npm-version-image]][npm-url]
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[![NPM Downloads][npm-downloads-image]][npm-url]
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[![Node.js Version][node-version-image]][node-version-url]
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[![Build Status][travis-image]][travis-url]
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[![Test Coverage][coveralls-image]][coveralls-url]
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Infer the content-type of a request.
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### Install
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This is a [Node.js](https://nodejs.org/en/) module available through the
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[npm registry](https://www.npmjs.com/). Installation is done using the
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[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
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```sh
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$ npm install type-is
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```
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## API
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```js
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var http = require('http')
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var typeis = require('type-is')
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http.createServer(function (req, res) {
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var istext = typeis(req, ['text/*'])
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res.end('you ' + (istext ? 'sent' : 'did not send') + ' me text')
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})
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```
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### typeis(request, types)
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Checks if the `request` is one of the `types`. If the request has no body,
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even if there is a `Content-Type` header, then `null` is returned. If the
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`Content-Type` header is invalid or does not matches any of the `types`, then
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`false` is returned. Otherwise, a string of the type that matched is returned.
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The `request` argument is expected to be a Node.js HTTP request. The `types`
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argument is an array of type strings.
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Each type in the `types` array can be one of the following:
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- A file extension name such as `json`. This name will be returned if matched.
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- A mime type such as `application/json`.
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- A mime type with a wildcard such as `*/*` or `*/json` or `application/*`.
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The full mime type will be returned if matched.
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- A suffix such as `+json`. This can be combined with a wildcard such as
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`*/vnd+json` or `application/*+json`. The full mime type will be returned
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if matched.
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Some examples to illustrate the inputs and returned value:
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<!-- eslint-disable no-undef -->
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```js
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// req.headers.content-type = 'application/json'
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typeis(req, ['json']) // => 'json'
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typeis(req, ['html', 'json']) // => 'json'
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typeis(req, ['application/*']) // => 'application/json'
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typeis(req, ['application/json']) // => 'application/json'
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typeis(req, ['html']) // => false
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```
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### typeis.hasBody(request)
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Returns a Boolean if the given `request` has a body, regardless of the
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`Content-Type` header.
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Having a body has no relation to how large the body is (it may be 0 bytes).
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This is similar to how file existence works. If a body does exist, then this
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indicates that there is data to read from the Node.js request stream.
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<!-- eslint-disable no-undef -->
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```js
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if (typeis.hasBody(req)) {
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// read the body, since there is one
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req.on('data', function (chunk) {
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// ...
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})
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}
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```
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### typeis.is(mediaType, types)
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Checks if the `mediaType` is one of the `types`. If the `mediaType` is invalid
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or does not matches any of the `types`, then `false` is returned. Otherwise, a
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string of the type that matched is returned.
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The `mediaType` argument is expected to be a
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[media type](https://tools.ietf.org/html/rfc6838) string. The `types` argument
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is an array of type strings.
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Each type in the `types` array can be one of the following:
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- A file extension name such as `json`. This name will be returned if matched.
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- A mime type such as `application/json`.
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- A mime type with a wildcard such as `*/*` or `*/json` or `application/*`.
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The full mime type will be returned if matched.
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- A suffix such as `+json`. This can be combined with a wildcard such as
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`*/vnd+json` or `application/*+json`. The full mime type will be returned
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if matched.
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Some examples to illustrate the inputs and returned value:
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<!-- eslint-disable no-undef -->
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```js
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var mediaType = 'application/json'
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typeis.is(mediaType, ['json']) // => 'json'
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typeis.is(mediaType, ['html', 'json']) // => 'json'
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typeis.is(mediaType, ['application/*']) // => 'application/json'
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typeis.is(mediaType, ['application/json']) // => 'application/json'
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typeis.is(mediaType, ['html']) // => false
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```
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## Examples
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### Example body parser
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```js
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var express = require('express')
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var typeis = require('type-is')
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var app = express()
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app.use(function bodyParser (req, res, next) {
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if (!typeis.hasBody(req)) {
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return next()
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}
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switch (typeis(req, ['urlencoded', 'json', 'multipart'])) {
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case 'urlencoded':
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// parse urlencoded body
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throw new Error('implement urlencoded body parsing')
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case 'json':
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// parse json body
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throw new Error('implement json body parsing')
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case 'multipart':
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// parse multipart body
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throw new Error('implement multipart body parsing')
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default:
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// 415 error code
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res.statusCode = 415
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res.end()
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break
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}
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})
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```
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## License
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[MIT](LICENSE)
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[coveralls-image]: https://badgen.net/coveralls/c/github/jshttp/type-is/master
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[coveralls-url]: https://coveralls.io/r/jshttp/type-is?branch=master
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[node-version-image]: https://badgen.net/npm/node/type-is
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[node-version-url]: https://nodejs.org/en/download
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[npm-downloads-image]: https://badgen.net/npm/dm/type-is
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[npm-url]: https://npmjs.org/package/type-is
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[npm-version-image]: https://badgen.net/npm/v/type-is
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[travis-image]: https://badgen.net/travis/jshttp/type-is/master
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[travis-url]: https://travis-ci.org/jshttp/type-is
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