JarCastingtype-is
Infer the content-type of a request.
Install
This is a Node.js module available through the npm registry. Installation is done using the npm install command:
$ npm install type-is
API
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*/jsonorapplication/*. The full mime type will be returned if matched. - A suffix such as
+json. This can be combined with a wildcard such as*/vnd+jsonorapplication/*+json. The full mime type will be returned if matched.
Some examples to illustrate the inputs and returned value:
// 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.
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 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*/jsonorapplication/*. The full mime type will be returned if matched. - A suffix such as
+json. This can be combined with a wildcard such as*/vnd+jsonorapplication/*+json. The full mime type will be returned if matched.
Some examples to illustrate the inputs and returned value:
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
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
}
})
