You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
120 lines
3.3 KiB
120 lines
3.3 KiB
# fresh
|
|
|
|
[![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]
|
|
|
|
HTTP response freshness testing
|
|
|
|
## Installation
|
|
|
|
This is a [Node.js](https://nodejs.org/en/) module available through the
|
|
[npm registry](https://www.npmjs.com/). Installation is done using the
|
|
[`npm install` command](https://docs.npmjs.com/getting-started/installing-npm-packages-locally):
|
|
|
|
```
|
|
$ npm install fresh
|
|
```
|
|
|
|
## API
|
|
|
|
<!-- eslint-disable no-unused-vars -->
|
|
|
|
```js
|
|
var fresh = require('fresh')
|
|
```
|
|
|
|
### fresh(reqHeaders, resHeaders)
|
|
|
|
Check freshness of the response using request and response headers.
|
|
|
|
When the response is still "fresh" in the client's cache `true` is
|
|
returned, otherwise `false` is returned to indicate that the client
|
|
cache is now stale and the full response should be sent.
|
|
|
|
When a client sends the `Cache-Control: no-cache` request header to
|
|
indicate an end-to-end reload request, this module will return `false`
|
|
to make handling these requests transparent.
|
|
|
|
## Known Issues
|
|
|
|
This module is designed to only follow the HTTP specifications, not
|
|
to work-around all kinda of client bugs (especially since this module
|
|
typically does not recieve enough information to understand what the
|
|
client actually is).
|
|
|
|
There is a known issue that in certain versions of Safari, Safari
|
|
will incorrectly make a request that allows this module to validate
|
|
freshness of the resource even when Safari does not have a
|
|
representation of the resource in the cache. The module
|
|
[jumanji](https://www.npmjs.com/package/jumanji) can be used in
|
|
an Express application to work-around this issue and also provides
|
|
links to further reading on this Safari bug.
|
|
|
|
## Example
|
|
|
|
### API usage
|
|
|
|
<!-- eslint-disable no-redeclare, no-undef -->
|
|
|
|
```js
|
|
var reqHeaders = { 'if-none-match': '"foo"' }
|
|
var resHeaders = { 'etag': '"bar"' }
|
|
fresh(reqHeaders, resHeaders)
|
|
// => false
|
|
|
|
var reqHeaders = { 'if-none-match': '"foo"' }
|
|
var resHeaders = { 'etag': '"foo"' }
|
|
fresh(reqHeaders, resHeaders)
|
|
// => true
|
|
```
|
|
|
|
### Using with Node.js http server
|
|
|
|
```js
|
|
var fresh = require('fresh')
|
|
var http = require('http')
|
|
|
|
var server = http.createServer(function (req, res) {
|
|
// perform server logic
|
|
// ... including adding ETag / Last-Modified response headers
|
|
|
|
if (isFresh(req, res)) {
|
|
// client has a fresh copy of resource
|
|
res.statusCode = 304
|
|
res.end()
|
|
return
|
|
}
|
|
|
|
// send the resource
|
|
res.statusCode = 200
|
|
res.end('hello, world!')
|
|
})
|
|
|
|
function isFresh (req, res) {
|
|
return fresh(req.headers, {
|
|
'etag': res.getHeader('ETag'),
|
|
'last-modified': res.getHeader('Last-Modified')
|
|
})
|
|
}
|
|
|
|
server.listen(3000)
|
|
```
|
|
|
|
## License
|
|
|
|
[MIT](LICENSE)
|
|
|
|
[npm-image]: https://img.shields.io/npm/v/fresh.svg
|
|
[npm-url]: https://npmjs.org/package/fresh
|
|
[node-version-image]: https://img.shields.io/node/v/fresh.svg
|
|
[node-version-url]: https://nodejs.org/en/
|
|
[travis-image]: https://img.shields.io/travis/jshttp/fresh/master.svg
|
|
[travis-url]: https://travis-ci.org/jshttp/fresh
|
|
[coveralls-image]: https://img.shields.io/coveralls/jshttp/fresh/master.svg
|
|
[coveralls-url]: https://coveralls.io/r/jshttp/fresh?branch=master
|
|
[downloads-image]: https://img.shields.io/npm/dm/fresh.svg
|
|
[downloads-url]: https://npmjs.org/package/fresh
|