negotiator
Advanced tools
The negotiator npm package is a content negotiation library used to parse and match HTTP headers for various content types. It allows servers to select the best representation of a resource based on the client's capabilities and preferences, as expressed through HTTP headers.
Content-Type Negotiation
This feature allows the server to determine the best media type to respond with, based on the client's 'Accept' HTTP header.
const Negotiator = require('negotiator');
const availableMediaTypes = ['text/html', 'application/json'];
const negotiator = new Negotiator(request);
const bestMediaType = negotiator.mediaType(availableMediaTypes);Language Negotiation
This feature enables the server to select the best language for the response content based on the client's 'Accept-Language' HTTP header.
const Negotiator = require('negotiator');
const availableLanguages = ['en', 'es', 'fr'];
const negotiator = new Negotiator(request);
const bestLanguage = negotiator.language(availableLanguages);Encoding Negotiation
This feature allows the server to choose the best encoding for the response based on the client's 'Accept-Encoding' HTTP header.
const Negotiator = require('negotiator');
const availableEncodings = ['gzip', 'deflate'];
const negotiator = new Negotiator(request);
const bestEncoding = negotiator.encoding(availableEncodings);Charset Negotiation
This feature allows the server to determine the best charset for the response content based on the client's 'Accept-Charset' HTTP header.
const Negotiator = require('negotiator');
const availableCharsets = ['utf-8', 'iso-8859-1'];
const negotiator = new Negotiator(request);
const bestCharset = negotiator.charset(availableCharsets);The 'accepts' npm package is similar to 'negotiator' in that it also provides content negotiation capabilities. It is built on top of 'negotiator' and provides a higher-level API for handling 'Accept', 'Accept-Encoding', 'Accept-Language', and 'Accept-Charset' headers.
An HTTP content negotiator for Node.js
$ npm install negotiator
var Negotiator = require('negotiator')
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.
Returns the most preferred media type from the client.
Returns the most preferred media type from a list of available media types.
Returns an array of preferred media types ordered by the client preference.
Returns an array of preferred media types ordered by priority from a list of available media types.
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.
Returns the most preferred language from the client.
Returns the most preferred language from a list of available languages.
Returns an array of preferred languages ordered by the client preference.
Returns an array of preferred languages ordered by priority from a list of available languages.
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.
Returns the most preferred charset from the client.
Returns the most preferred charset from a list of available charsets.
Returns an array of preferred charsets ordered by the client preference.
Returns an array of preferred charsets ordered by priority from a list of available charsets.
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.
Returns the most preferred encoding from the client.
Returns the most preferred encoding from a list of available encodings.
Returns the most preferred encoding from a list of available encodings, while prioritizing based on preferred array between same-quality encodings.
Returns an array of preferred encodings ordered by the client preference.
Returns an array of preferred encodings ordered by priority from a list of available encodings.
Returns an array of preferred encodings ordered by priority from a list of
available encodings, while prioritizing based on preferred array between same-quality encodings.
The accepts module builds on this module and provides an alternative interface, mime type validation, and more.
FAQs
HTTP content negotiation
The npm package negotiator receives a total of 30,408,769 weekly downloads. As such, negotiator popularity was classified as popular.
We found that negotiator demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 3 open source maintainers collaborating on the project.
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