https://github.com/joshuawise/negotiated

A low-level, standards-compliant utility for parsing HTTP content negotiation headers
https://github.com/joshuawise/negotiated

accept content-negotiation http

Last synced: 26 days ago
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A low-level, standards-compliant utility for parsing HTTP content negotiation headers

• Host: GitHub
• URL: https://github.com/joshuawise/negotiated
• Owner: JoshuaWise
• License: mit
• Created: 2018-07-12T15:55:08.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2020-12-31T16:26:52.000Z (almost 4 years ago)
• Last Synced: 2024-11-14T11:44:19.453Z (about 1 month ago)
• Topics: accept, content-negotiation, http
• Language: JavaScript
• Homepage:
• Size: 16.6 KB
• Stars: 2
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# negotiated [![Build Status](https://travis-ci.org/JoshuaWise/negotiated.svg?branch=master)](https://travis-ci.org/JoshuaWise/negotiated)

This is a low-level utility for correctly parsing the HTTP content negotiation headers. It doesn't interpret the parsed values in any way, except for ensuring that they are syntactically correct.

## Installation

```bash

npm install --save negotiated

```

## Usage

```js

const negotiated = require('negotiated');

const best = Array.from(negotiated.languages('fr;q=0.4, ja-JP;q=0.2, de-DE;q=0.7, en;q=0.5'))

  .reduce((a, b) => a.weight >= b.weight ? a : b);

console.log(best.language); // => "de-de"

```

This package exports six functions:

- `mediaTypes()`: parses the Accept header, emitting `{ type, params, weight, extensions }`

- `charsets()`: parses the Accept-Charset header, emitting `{ charset, weight }`

- `encodings()`: parses the Accept-Encoding header, emitting `{ encoding, weight }`

- `languages()`: parses the Accept-Language header, emitting `{ language, weight }`

- `transferEncodings()`: parses the TE header, emitting `{ encoding, params, weight }`

- `parameters()`: parses the `params` and `extensions` found above, emitting `{ key, value }`

Each of the exported functions takes a string as the only argument. An iterator is returned, which parses one comma-separated item at a time. If the input string is invalid (according to [RFC 7230](https://tools.ietf.org/html/rfc7230) or [RFC 7231](https://tools.ietf.org/html/rfc7231)), an error will be thrown mid-iteration.

## Examples

#### Iterating over the Accept-Encoding header

```js

const negotiated = require('negotiated');

for (const { encoding, weight } of negotiated.encodings('gzip;q=0.5, my-custom-encoding;q=1')) {

  if (weight > 0.8) console.log(`${encoding} is desired`);

}

// => "my-custom-encoding is desired"

```

#### Parsing media parameters

```js

const negotiated = require('negotiated');

const [{ params }] = Array.from(negotiated.mediaTypes('application/json; CHARSET="utf-8"'));

console.log(Array.from(negotiated.parameters(params))); // => [{ key: 'charset', value: 'utf-8' }]

```