node_modules/on-headers/README.md

   1 # on-headers
   2
   3 [![NPM Version][npm-version-image]][npm-url]
   4 [![NPM Downloads][npm-downloads-image]][npm-url]
   5 [![Node.js Version][node-version-image]][node-version-url]
   6 [![Build Status][travis-image]][travis-url]
   7 [![Test Coverage][coveralls-image]][coveralls-url]
   8
   9 Execute a listener when a response is about to write headers.
  10
  11 ## Installation
  12
  13 This is a [Node.js](https://nodejs.org/en/) module available through the
  14 [npm registry](https://www.npmjs.com/). Installation is done using the
  15 [`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
  16
  17 ```sh
  18 $ npm install on-headers
  19 ```
  20
  21 ## API
  22
  23 <!-- eslint-disable no-unused-vars -->
  24
  25 ```js
  26 var onHeaders = require('on-headers')
  27 ```
  28
  29 ### onHeaders(res, listener)
  30
  31 This will add the listener `listener` to fire when headers are emitted for `res`.
  32 The listener is passed the `response` object as it's context (`this`). Headers are
  33 considered to be emitted only once, right before they are sent to the client.
  34
  35 When this is called multiple times on the same `res`, the `listener`s are fired
  36 in the reverse order they were added.
  37
  38 ## Examples
  39
  40 ```js
  41 var http = require('http')
  42 var onHeaders = require('on-headers')
  43
  44 http
  45   .createServer(onRequest)
  46   .listen(3000)
  47
  48 function addPoweredBy () {
  49   // set if not set by end of request
  50   if (!this.getHeader('X-Powered-By')) {
  51     this.setHeader('X-Powered-By', 'Node.js')
  52   }
  53 }
  54
  55 function onRequest (req, res) {
  56   onHeaders(res, addPoweredBy)
  57
  58   res.setHeader('Content-Type', 'text/plain')
  59   res.end('hello!')
  60 }
  61 ```
  62
  63 ## Testing
  64
  65 ```sh
  66 $ npm test
  67 ```
  68
  69 ## License
  70
  71 [MIT](LICENSE)
  72
  73 [coveralls-image]: https://badgen.net/coveralls/c/github/jshttp/on-headers/master
  74 [coveralls-url]: https://coveralls.io/r/jshttp/on-headers?branch=master
  75 [node-version-image]: https://badgen.net/npm/node/on-headers
  76 [node-version-url]: https://nodejs.org/en/download
  77 [npm-downloads-image]: https://badgen.net/npm/dm/on-headers
  78 [npm-url]: https://npmjs.org/package/on-headers
  79 [npm-version-image]: https://badgen.net/npm/v/on-headers
  80 [travis-image]: https://badgen.net/travis/jshttp/on-headers/master
  81 [travis-url]: https://travis-ci.org/jshttp/on-headers