type-is

Infer the content-type of a request.

Install

$ npm install type-is

API

import{createServer}from"http";import*astypeisfrom"type-is";http.createServer(function(req,res){varistext=typeis.request(req,["text/*"]);res.end("you "+(istext ? "sent" : "did not send")+" me text");});

request(req, 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:

// req.headers.content-type = 'application/json'request(req,["json"]);// => 'json'request(req,["html","json"]);// => 'json'request(req,["application/*"]);// => 'application/json'request(req,["application/json"]);// => 'application/json'request(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 onereq.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 */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:

varmediaType="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

typeis.match(expected, actual)

Match the type string expected with actual, taking in to account wildcards. A wildcard can only be in the type of the subtype part of a media type and only in the expected value (as actual should be the real media type to match). A suffix can still be included even with a wildcard subtype. If an input is malformed, false will be returned.

typeis.match("text/html","text/html");// => truetypeis.match("*/html","text/html");// => truetypeis.match("text/*","text/html");// => truetypeis.match("*/*","text/html");// => truetypeis.match("*/*+json","application/x-custom+json");// => true

typeis.normalize(type)

Normalize a type string. This works by performing the following:

• If the type is not a string, false is returned.
• If the string starts with + (so it is a +suffix shorthand like +json), then it is expanded to contain the complete wildcard notation of */*+suffix.
• If the string contains a /, then it is returned as the type.
• Else the string is assumed to be a file extension and the mapped media type is returned, or false is there is no mapping.

This includes two special mappings:

• 'multipart' -> 'multipart/*'
• 'urlencoded' -> 'application/x-www-form-urlencoded'

Examples

Example body parser

varexpress=require("express");vartypeis=require("type-is");varapp=express();app.use(functionbodyParser(req,res,next){if(!typeis.hasBody(req)){returnnext();}switch(typeis.request(req,["urlencoded","json","multipart"])){case"urlencoded":
// parse urlencoded bodythrownewError("implement urlencoded body parsing");case"json":
// parse json bodythrownewError("implement json body parsing");case"multipart":
// parse multipart bodythrownewError("implement multipart body parsing");default:
// 415 error coderes.statusCode=415;res.end();break;}});

License

MIT