Content-Type parsing

Usage

Parse

var MediaType = require('contenttype');

var type = MediaType.parseMedia('text/html;q=1');
console.log(type);
// MediaType { type: 'text/html', params: {}, q: 1 }

Express

var MediaType = require('contenttype');
var representations = [
  'application/json',
  'text/html'
];

app.use(function (req, res, next) {
  var representation = MediaType.select(representations, req.headers.accept);
  if (representation === null) {
    res.status(406);
    res.json({error: "No valid content-type found for specified Accept header"});
  }
  res.rep = representation;
  next();
});

app.get('/', function (req, res, next) {
  res.set("Content-Type", res.rep);
  if (res.rep === "application/json") {
    res.json({message: "hello"});
  } else if (res.rep === "text/html") {
    res.send("hello");
  }
});

new MediaType(type, [parameters])

The MediaType "class" represents a parsed Media Type. For use in HTTP, the q parameter will be parsed as a float. Other parameters are available through the params object.

Example

console.log(new MediaType('text/html;l=3;q=0.7', { p: 4 }));
// MediaType { type: 'text/html', params: { l: '3', p: '4' }, q: 0.7 }

Example

console.log(new MediaType('text/html;l=3', 'p=4;l=5;q=1'));
// MediaType { type: 'text/html', params: { l: '5', p: '4' }, q: 1 }

Example

var type = new MediaType('text/html;l=3', 'p=4;l=5');
console.log(new MediaType(type, 'p=6;'));
// MediaType { type: 'text/html', params: { l: '5', p: '6' } }

toString()

Convert a MediaType object to a string

Example

var type = new MediaType('text/html;l=3;q=0.5');
console.log(type.toString());
// "text/html; l=5; q=0.5"

parseMedia(type)

Parse a media type. Returns a new instance of MediaType.

Example

var type = MediaType.parseMedia('text/html;l=3');
console.log(type);
// MediaType { type: 'text/html', params: { l: '3' } }

splitQuotedString(str, [delimiter=';'], [quote='"'])

Splits a string by a delimiter character (default: semicolon), ignoring sections enclosed by quotes (default: double quote).

Example

var items = MediaType.splitQuotedString("text/html;level=2;q=1");
console.log(items);
// [ 'text/html', 'level=2', 'q=1' ]

splitContentTypes(str)

Convenience method for splitQuotedString(str, ',', '"');. Splits an Accept (or similar) header into an Array of content-types strings

Example

var types = MediaType.splitContentTypes("text/html;level=2;q=1,application/json,*/*");
console.log(types);
// [ 'text/html;level=2;q=1', 'application/json', '*/*' ]

Example

var types = MediaType.splitContentTypes('application/json, text/html').map(MediaType.parseMedia);
console.log(types);
// [ MediaType { type: 'application/json', params: {} }, MediaType { type: 'text/html', params: {} } ]

select(representations, accept)

Pick an ideal representation to send, given an array of representations (strings or MediaTypes) to choose from, and the client-preferred Accept list (as a string, an array of strings, or an array of MediaTypes). Multiplies client type's quality factor by server type's quality factor

Example

var representations = [
  "text/html; q=0.7",
  "text/plain; q=0.5",
  "image/jpeg"
];
var accept = MediaType.splitContentTypes('text/html;q=0.7, text/plain, */*;q=0.1');
var selected = (MediaType.select(representations, accept)).toString();
// text/html gets q=0.49, text/plain gets q=0.5, image/jpeg gets q=0.1
console.log(selected);
// "text/plain"

mediaCmp(a, b)

Accepts two MediaType instances and tests them for being a subset/superset.

If a is a superset of b (b is smaller than a), return 1. If b is a superset of a, return -1. If they are the exact same, return 0. If they are disjoint, return null.

The q-value, if any, is ignored.

Example

mediaCmp(parseMedia('text/html'), parseMedia('text/html')) === 0
mediaCmp(parseMedia('*/*'), parseMedia('text/html')) === 1
mediaCmp(parseMedia('text/html;level=1'), parseMedia('text/html')) === -1
mediaCmp(parseMedia('text/html;level=1.2.*'), parseMedia('text/html;level=1.2.3')) === 0
mediaCmp(parseMedia('application/json;profile="v1.json"'), parseMedia('application/json;profile="v2.json"')) === null

Related

• media-typer - if you need simple RFC 6838 media type parser and formatter.