102 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Markdown
		
	
	
	
		
		
			
		
	
	
			102 lines
		
	
	
		
			2.7 KiB
		
	
	
	
		
			Markdown
		
	
	
	
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								# vary
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								[![NPM Version][npm-image]][npm-url]
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								[![NPM Downloads][downloads-image]][downloads-url]
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								[![Node.js Version][node-version-image]][node-version-url]
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								[![Build Status][travis-image]][travis-url]
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								[![Test Coverage][coveralls-image]][coveralls-url]
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								Manipulate the HTTP Vary header
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								## Installation
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								This is a [Node.js](https://nodejs.org/en/) module available through the
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								[npm registry](https://www.npmjs.com/). Installation is done using the
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								[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally): 
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								```sh
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								$ npm install vary
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								```
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								## API
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								<!-- eslint-disable no-unused-vars -->
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								```js
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								var vary = require('vary')
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								```
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								### vary(res, field)
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								Adds the given header `field` to the `Vary` response header of `res`.
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								This can be a string of a single field, a string of a valid `Vary`
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								header, or an array of multiple fields.
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								This will append the header if not already listed, otherwise leaves
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								it listed in the current location.
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								<!-- eslint-disable no-undef -->
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								```js
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								// Append "Origin" to the Vary header of the response
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								vary(res, 'Origin')
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								```
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								### vary.append(header, field)
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								Adds the given header `field` to the `Vary` response header string `header`.
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								This can be a string of a single field, a string of a valid `Vary` header,
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								or an array of multiple fields.
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								This will append the header if not already listed, otherwise leaves
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								it listed in the current location. The new header string is returned.
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								<!-- eslint-disable no-undef -->
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								```js
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								// Get header string appending "Origin" to "Accept, User-Agent"
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								vary.append('Accept, User-Agent', 'Origin')
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								```
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								## Examples
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								### Updating the Vary header when content is based on it
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								```js
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								var http = require('http')
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								var vary = require('vary')
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								http.createServer(function onRequest (req, res) {
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								  // about to user-agent sniff
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								  vary(res, 'User-Agent')
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								  var ua = req.headers['user-agent'] || ''
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								  var isMobile = /mobi|android|touch|mini/i.test(ua)
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								  // serve site, depending on isMobile
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								  res.setHeader('Content-Type', 'text/html')
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								  res.end('You are (probably) ' + (isMobile ? '' : 'not ') + 'a mobile user')
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								})
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								```
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								## Testing
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								```sh
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								$ npm test
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								```
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								## License
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								[MIT](LICENSE)
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								[npm-image]: https://img.shields.io/npm/v/vary.svg
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								[npm-url]: https://npmjs.org/package/vary
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								[node-version-image]: https://img.shields.io/node/v/vary.svg
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								[node-version-url]: https://nodejs.org/en/download
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								[travis-image]: https://img.shields.io/travis/jshttp/vary/master.svg
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								[travis-url]: https://travis-ci.org/jshttp/vary
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								[coveralls-image]: https://img.shields.io/coveralls/jshttp/vary/master.svg
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								[coveralls-url]: https://coveralls.io/r/jshttp/vary
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								[downloads-image]: https://img.shields.io/npm/dm/vary.svg
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								[downloads-url]: https://npmjs.org/package/vary
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