77 lines
1.9 KiB
Markdown
77 lines
1.9 KiB
Markdown
|
# on-headers
|
||
|
|
|
||
|
|
[![NPM Version][npm-image]][npm-url]
|
||
|
|
[![NPM Downloads][downloads-image]][downloads-url]
|
||
|
|
[![Node.js Version][node-version-image]][node-version-url]
|
||
|
|
[![Build Status][travis-image]][travis-url]
|
||
|
|
[![Test Coverage][coveralls-image]][coveralls-url]
|
||
|
|
|
||
|
|
Execute a listener when a response is about to write headers.
|
||
|
|
|
||
|
|
## Installation
|
||
|
|
|
||
|
|
```sh
|
||
|
|
$ npm install on-headers
|
||
|
|
```
|
||
|
|
|
||
|
|
## API
|
||
|
|
|
||
|
|
```js
|
||
|
|
var onHeaders = require('on-headers')
|
||
|
|
```
|
||
|
|
|
||
|
|
### onHeaders(res, listener)
|
||
|
|
|
||
|
|
This will add the listener `listener` to fire when headers are emitted for `res`.
|
||
|
|
The listener is passed the `response` object as it's context (`this`). Headers are
|
||
|
|
considered to be emitted only once, right before they are sent to the client.
|
||
|
|
|
||
|
|
When this is called multiple times on the same `res`, the `listener`s are fired
|
||
|
|
in the reverse order they were added.
|
||
|
|
|
||
|
|
## Examples
|
||
|
|
|
||
|
|
```js
|
||
|
|
var http = require('http')
|
||
|
|
var onHeaders = require('on-headers')
|
||
|
|
|
||
|
|
http
|
||
|
|
.createServer(onRequest)
|
||
|
|
.listen(3000)
|
||
|
|
|
||
|
|
function addPoweredBy() {
|
||
|
|
// set if not set by end of request
|
||
|
|
if (!this.getHeader('X-Powered-By')) {
|
||
|
|
this.setHeader('X-Powered-By', 'Node.js')
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
function onRequest(req, res) {
|
||
|
|
onHeaders(res, addPoweredBy)
|
||
|
|
|
||
|
|
res.setHeader('Content-Type', 'text/plain')
|
||
|
|
res.end('hello!')
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
## Testing
|
||
|
|
|
||
|
|
```sh
|
||
|
|
$ npm test
|
||
|
|
```
|
||
|
|
|
||
|
|
## License
|
||
|
|
|
||
|
|
[MIT](LICENSE)
|
||
|
|
|
||
|
|
[npm-image]: https://img.shields.io/npm/v/on-headers.svg
|
||
|
|
[npm-url]: https://npmjs.org/package/on-headers
|
||
|
|
[node-version-image]: https://img.shields.io/node/v/on-headers.svg
|
||
|
|
[node-version-url]: http://nodejs.org/download/
|
||
|
|
[travis-image]: https://img.shields.io/travis/jshttp/on-headers/master.svg
|
||
|
|
[travis-url]: https://travis-ci.org/jshttp/on-headers
|
||
|
|
[coveralls-image]: https://img.shields.io/coveralls/jshttp/on-headers/master.svg
|
||
|
|
[coveralls-url]: https://coveralls.io/r/jshttp/on-headers?branch=master
|
||
|
|
[downloads-image]: https://img.shields.io/npm/dm/on-headers.svg
|
||
|
|
[downloads-url]: https://npmjs.org/package/on-headers
|