What is accepts?
The 'accepts' npm package is a utility for content negotiation in Node.js. It allows a server to interpret the content types that a client can handle and respond with the most appropriate content type. It is commonly used in HTTP server frameworks like Express to simplify the process of determining what MIME types the client accepts in the 'Accept' HTTP header.
What are accepts's main functionalities?
Content Type Negotiation
This code demonstrates how to use the 'accepts' package to determine the best response content type based on the client's 'Accept' header. The server responds with either JSON, HTML, or plain text.
const accepts = require('accepts');
const http = require('http');
http.createServer(function (req, res) {
var accept = accepts(req);
var preferredType = accept.type(['json', 'html']);
if (preferredType === 'json') {
res.setHeader('Content-Type', 'application/json');
res.end(JSON.stringify({ message: 'Hello, JSON!' }));
} else if (preferredType === 'html') {
res.setHeader('Content-Type', 'text/html');
res.end('<p>Hello, HTML!</p>');
} else {
res.setHeader('Content-Type', 'text/plain');
res.end('Hello, plain text!');
}
}).listen(3000);
Language Negotiation
This code snippet shows how to use the 'accepts' package to determine the client's preferred language from the 'Accept-Language' header and respond accordingly.
const accepts = require('accepts');
const http = require('http');
http.createServer(function (req, res) {
var accept = accepts(req);
var preferredLanguage = accept.language(['en', 'es', 'fr']);
res.end('Preferred language: ' + preferredLanguage);
}).listen(3000);
Encoding Negotiation
This example illustrates how to use the 'accepts' package to negotiate the content encoding that the client supports, such as 'gzip' or 'deflate'.
const accepts = require('accepts');
const http = require('http');
http.createServer(function (req, res) {
var accept = accepts(req);
var preferredEncoding = accept.encoding(['gzip', 'deflate']);
res.end('Preferred encoding: ' + preferredEncoding);
}).listen(3000);
Charset Negotiation
This code sample demonstrates how to use the 'accepts' package to determine which charset the client prefers, such as 'utf-8' or 'iso-8859-1'.
const accepts = require('accepts');
const http = require('http');
http.createServer(function (req, res) {
var accept = accepts(req);
var preferredCharset = accept.charset(['utf-8', 'iso-8859-1']);
res.end('Preferred charset: ' + preferredCharset);
}).listen(3000);
Other packages similar to accepts
negotiator
The 'negotiator' package is similar to 'accepts' and provides an HTTP content negotiation algorithm that is compliant with RFC 7231. It offers more detailed control over the negotiation process compared to 'accepts', but it might be more complex to use for simple scenarios.
negotiate
The 'negotiate' package is another alternative for content negotiation in Node.js. It is designed to be a simple and lightweight solution, but it may not be as feature-rich or widely used as 'accepts'.
Accepts
![Coverage Status](https://img.shields.io/coveralls/expressjs/accepts.svg?branch=master)
Higher level content negotation based on negotiator. Extracted from koa for general use.
In addition to negotatior, it allows:
- Allows types as an array or arguments list, ie
(['text/html', 'application/json'])
as well as ('text/html', 'application/json')
. - Allows type shorthands such as
json
. - Returns
false
when no types match - Treats non-existent headers as
*
API
var accept = new Accepts(req)
var accepts = require('accepts')
http.createServer(function (req, res) {
var accept = accepts(req)
})
accept[property]()
Returns all the explicitly accepted content property as an array in descending priority.
accept.types()
accept.encodings()
accept.charsets()
accept.languages()
They are also aliased in singular form such as accept.type()
. accept.languages()
is also aliased as accept.langs()
, etc.
Note: you should almost never do this in a real app as it defeats the purpose of content negotiation.
Example:
var encodings = accept.encodings()
Since you probably don't support sdch
, you should just supply the encodings you support:
var encoding = accept.encodings('gzip', 'deflate')
accept[property](values, ...)
You can either have values
be an array or have an argument list of values.
If the client does not accept any values
, false
will be returned.
If the client accepts any values
, the preferred value
will be return.
For accept.types()
, shorthand mime types are allowed.
Example:
accept.types('json')
accept.types('html', 'json')
accept.types('html')
accept.types()
accept.types('text/html', 'text/json')
License
The MIT License (MIT)
Copyright (c) 2013 Jonathan Ong me@jongleberry.com
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.