# vary

> Manipulate the HTTP Vary header

Latest version **1.1.2** (published 2017-09-24) · MIT license · 0 weekly downloads

## Install

```sh
npm install vary
pnpm add vary
yarn add vary
bun add vary
```

## Health

**Score 33/100 (F)** — status: abandoned.

Positive: has types package; no vulnerabilities; high quality score.

Warnings: low downloads; no esm support.

Negative: abandoned.

## Facts

| | |
|---|---|
| Version | 1.1.2 |
| Published | 2017-09-24 |
| First published | 2014-06-04 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | separate (@types/vary) |
| Module format | CommonJS |
| Node | >= 0.8 |
| Dependencies | 0 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 65 |
| Author | Douglas Christopher Wilson |
| Maintainers | dougwilson |
| Keywords | http, res, vary |

## Links

- npm: https://www.npmjs.com/package/vary
- Repository: https://github.com/jshttp/vary
- Homepage: https://github.com/jshttp/vary#readme
- Issues: https://github.com/jshttp/vary/issues
- npm.io page: https://npm.io/package/vary

## Alternatives

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- [@bbc/http-transport-cache](https://npm.io/package/@bbc/http-transport-cache.md) — 1.2K weekly downloads

## Recent versions

- 1.1.2 (latest) — 2017-09-24
- 1.1.1 — 2017-03-20
- 1.1.0 — 2015-09-30
- 1.0.1 — 2015-07-09
- 1.0.0 — 2014-08-10
- 0.1.0 — 2014-06-05
- 0.0.0 — 2014-06-04

## README

# vary

[![NPM Version][npm-image]][npm-url]
[![NPM Downloads][downloads-image]][downloads-url]
[![Node.js Version][node-version-image]][node-version-url]
[![Build Status][travis-image]][travis-url]
[![Test Coverage][coveralls-image]][coveralls-url]

Manipulate the HTTP Vary header

## Installation

This is a [Node.js](https://nodejs.org/en/) module available through the
[npm registry](https://www.npmjs.com/). Installation is done using the
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally): 

```sh
$ npm install vary
```

## API

<!-- eslint-disable no-unused-vars -->

```js
var vary = require('vary')
```

### vary(res, field)

Adds the given header `field` to the `Vary` response header of `res`.
This can be a string of a single field, a string of a valid `Vary`
header, or an array of multiple fields.

This will append the header if not already listed, otherwise leaves
it listed in the current location.

<!-- eslint-disable no-undef -->

```js
// Append "Origin" to the Vary header of the response
vary(res, 'Origin')
```

### vary.append(header, field)

Adds the given header `field` to the `Vary` response header string `header`.
This can be a string of a single field, a string of a valid `Vary` header,
or an array of multiple fields.

This will append the header if not already listed, otherwise leaves
it listed in the current location. The new header string is returned.

<!-- eslint-disable no-undef -->

```js
// Get header string appending "Origin" to "Accept, User-Agent"
vary.append('Accept, User-Agent', 'Origin')
```

## Examples

### Updating the Vary header when content is based on it

```js
var http = require('http')
var vary = require('vary')

http.createServer(function onRequest (req, res) {
  // about to user-agent sniff
  vary(res, 'User-Agent')

  var ua = req.headers['user-agent'] || ''
  var isMobile = /mobi|android|touch|mini/i.test(ua)

  // serve site, depending on isMobile
  res.setHeader('Content-Type', 'text/html')
  res.end('You are (probably) ' + (isMobile ? '' : 'not ') + 'a mobile user')
})
```

## Testing

```sh
$ npm test
```

## License

[MIT](LICENSE)

[npm-image]: https://img.shields.io/npm/v/vary.svg
[npm-url]: https://npmjs.org/package/vary
[node-version-image]: https://img.shields.io/node/v/vary.svg
[node-version-url]: https://nodejs.org/en/download
[travis-image]: https://img.shields.io/travis/jshttp/vary/master.svg
[travis-url]: https://travis-ci.org/jshttp/vary
[coveralls-image]: https://img.shields.io/coveralls/jshttp/vary/master.svg
[coveralls-url]: https://coveralls.io/r/jshttp/vary
[downloads-image]: https://img.shields.io/npm/dm/vary.svg
[downloads-url]: https://npmjs.org/package/vary

---
_Source: https://npm.io/package/vary · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._