# negotiator
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[![NPM Downloads][downloads-image]][downloads-url]
[![Node.js Version][node-version-image]][node-version-url]
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[![Test Coverage][coveralls-image]][coveralls-url]
An HTTP content negotiator for Node.js
## Installation
```sh
$ npm install negotiator
```
## API
```js
var Negotiator = require('negotiator')
```
### Accept Negotiation
```js
availableMediaTypes = ['text/html', 'text/plain', 'application/json']
// The negotiator constructor receives a request object
negotiator = new Negotiator(request)
// Let's say Accept header is 'text/html, application/*;q=0.2, image/jpeg;q=0.8'
negotiator.mediaTypes()
// -> ['text/html', 'image/jpeg', 'application/*']
negotiator.mediaTypes(availableMediaTypes)
// -> ['text/html', 'application/json']
negotiator.mediaType(availableMediaTypes)
// -> 'text/html'
```
You can check a working example at `examples/accept.js`.
#### Methods
##### mediaType()
Returns the most preferred media type from the client.
##### mediaType(availableMediaType)
Returns the most preferred media type from a list of available media types.
##### mediaTypes()
Returns an array of preferred media types ordered by the client preference.
##### mediaTypes(availableMediaTypes)
Returns an array of preferred media types ordered by priority from a list of
available media types.
### Accept-Language Negotiation
```js
negotiator = new Negotiator(request)
availableLanguages = ['en', 'es', 'fr']
// Let's say Accept-Language header is 'en;q=0.8, es, pt'
negotiator.languages()
// -> ['es', 'pt', 'en']
negotiator.languages(availableLanguages)
// -> ['es', 'en']
language = negotiator.language(availableLanguages)
// -> 'es'
```
You can check a working example at `examples/language.js`.
#### Methods
##### language()
Returns the most preferred language from the client.
##### language(availableLanguages)
Returns the most preferred language from a list of available languages.
##### languages()
Returns an array of preferred languages ordered by the client preference.
##### languages(availableLanguages)
Returns an array of preferred languages ordered by priority from a list of
available languages.
### Accept-Charset Negotiation
```js
availableCharsets = ['utf-8', 'iso-8859-1', 'iso-8859-5']
negotiator = new Negotiator(request)
// Let's say Accept-Charset header is 'utf-8, iso-8859-1;q=0.8, utf-7;q=0.2'
negotiator.charsets()
// -> ['utf-8', 'iso-8859-1', 'utf-7']
negotiator.charsets(availableCharsets)
// -> ['utf-8', 'iso-8859-1']
negotiator.charset(availableCharsets)
// -> 'utf-8'
```
You can check a working example at `examples/charset.js`.
#### Methods
##### charset()
Returns the most preferred charset from the client.
##### charset(availableCharsets)
Returns the most preferred charset from a list of available charsets.
##### charsets()
Returns an array of preferred charsets ordered by the client preference.
##### charsets(availableCharsets)
Returns an array of preferred charsets ordered by priority from a list of
available charsets.
### Accept-Encoding Negotiation
```js
availableEncodings = ['identity', 'gzip']
negotiator = new Negotiator(request)
// Let's say Accept-Encoding header is 'gzip, compress;q=0.2, identity;q=0.5'
negotiator.encodings()
// -> ['gzip', 'identity', 'compress']
negotiator.encodings(availableEncodings)
// -> ['gzip', 'identity']
negotiator.encoding(availableEncodings)
// -> 'gzip'
```
You can check a working example at `examples/encoding.js`.
#### Methods
##### encoding()
Returns the most preferred encoding from the client.
##### encoding(availableEncodings)
Returns the most preferred encoding from a list of available encodings.
##### encodings()
Returns an array of preferred encodings ordered by the client preference.
##### encodings(availableEncodings)
Returns an array of preferred encodings ordered by priority from a list of
available encodings.
## See Also
The [accepts](https://npmjs.org/package/accepts#readme) module builds on
this module and provides an alternative interface, mime type validation,
and more.
## License
[MIT](LICENSE)
[npm-image]: https://img.shields.io/npm/v/negotiator.svg
[npm-url]: https://npmjs.org/package/negotiator
[node-version-image]: https://img.shields.io/node/v/negotiator.svg
[node-version-url]: https://nodejs.org/en/download/
[coveralls-image]: https://img.shields.io/coveralls/jshttp/negotiator/master.svg
[coveralls-url]: https://coveralls.io/r/jshttp/negotiator?branch=master
[downloads-image]: https://img.shields.io/npm/dm/negotiator.svg
[downloads-url]: https://npmjs.org/package/negotiator
[github-actions-ci-image]: https://img.shields.io/github/workflow/status/jshttp/negotiator/ci/master?label=ci
[github-actions-ci-url]: https://github.com/jshttp/negotiator/actions/workflows/ci.yml