es-vary

vary rewrite in TypeScript with ESM and CommonJS targets

Manipulate the HTTP Vary header

Install

pnpm i es-vary

API

import { vary, append } from 'es-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.

vary(res, 'Origin')

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.

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

Examples

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