es-vary

![Vulnerabilities][snyk-image]
[![Version][npm-v-image]][npm-url]
[![Node Version][node-version-image]][node-version-url]

> vary rewrite in TypeScript with ESM and CommonJS targets

Manipulate the HTTP Vary header

Install

``sh
pnpm i es-vary
`

API

`ts
import { vary, append } from 'es-vary'
`

$3

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.

`ts
vary(res, 'Origin')
`

$3

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.

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

Examples

`ts
import { createServer } from 'http'
import { vary } from 'es-vary'

createServer((req, res) => {
// about to user-agent sniff
vary(res, 'User-Agent')

const ua = req.headers['user-agent'] || ''
const 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')
})
``

License

MIT © v1rtl

[node-version-image]: https://img.shields.io/node/v/es-vary.svg?style=flat-square
[node-version-url]: https://nodejs.org
[snyk-image]: https://img.shields.io/snyk/vulnerabilities/npm/es-vary.svg?style=flat-square
[npm-v-image]: https://img.shields.io/npm/v/es-vary.svg?style=flat-square
[npm-url]: https://www.npmjs.com/package/es-vary