@goa/vary


@goa/vary is a fork of Manipulate the HTTP Vary header rewritten in ES6 Modules.

``sh
yarn add @goa/vary
`

The original module has been updated to be used in @goa/koa: _Koa_ web server compiled with _Google Closure Compiler_ using Depack into a single file library (0 dependencies).

Table Of Contents

- Table Of Contents
- API
- vary(res: http.ServerResponse, field: string|Array)
- append(header: string, field: string|Array): string
- Copyright

API

The package is available by importing its default and named functions:

`js
import vary, { append } from '@goa/vary'
`

vary(
  res: http.ServerResponse,
  field: string|Array,
): void

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.

`js
/ alanode example/ /
import vary from '@goa/vary'
import aqt from '@rqt/aqt'
import { createServer } from 'http'

const server = createServer((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')
})

server.listen(async () => {
const url = http://localhost:${server.address().port}
const { headers } = await aqt(url)
console.log(headers)
server.close()
})
`
`js
{ vary: 'User-Agent',
'content-type': 'text/html',
date: 'Sat, 20 Apr 2019 11:57:51 GMT',
connection: 'close',
'content-length': '36' }
`

append(
  header: string,
  field: string|Array,
): string

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.

`js

append('Accept, User-Agent', 'Origin')
`

`js
import { append } from '@goa/vary'

// Get header string appending "Origin" to "Accept, User-Agent"
console.log(append('Accept, User-Agent', 'Origin'))
console.log(append('Accept-Encoding, Accept', '*'))
console.log(append('Accept-Encoding, Accept, *', 'Origin'))
`
`
Accept, User-Agent, Origin
*
*
``

Copyright

Original Author: Douglas Wilson

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