Infer the content-type of a request.
This is a Node.js module available through the
npm registry. Installation is done using the
npm install command:
sh
$ npm install type-is
```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’) }) ```
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:
json. This name will be returned if matched.application/json.*/* or */json or application/*.
The full mime type will be returned if matched.+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 ```
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) { // … }) } ```
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:
json. This name will be returned if matched.application/json.*/* or */json or application/*.
The full mime type will be returned if matched.+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 ```
```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 } }) ```