Name: fresh
Owner: jshttp
Description: HTTP request freshness testing
Created: 2012-06-10 19:09:09.0
Updated: 2018-01-13 05:08:11.0
Pushed: 2017-09-26 18:17:16.0
Size: 67
Language: JavaScript
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HTTP response freshness testing
This is a Node.js module available through the
npm registry. Installation is done using the
npm install command:
m install fresh
fresh = require('fresh')
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.
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 receive 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 can be used in an Express application to work-around this issue and also provides links to further reading on this Safari bug.
reqHeaders = { 'if-none-match': '"foo"' }
resHeaders = { 'etag': '"bar"' }
h(reqHeaders, resHeaders)
> false
reqHeaders = { 'if-none-match': '"foo"' }
resHeaders = { 'etag': '"foo"' }
h(reqHeaders, resHeaders)
> true
fresh = require('fresh')
http = require('http')
server = http.createServer(function (req, res) {
perform server logic
... including adding ETag / Last-Modified response headers
(isFresh(req, res)) {
// client has a fresh copy of resource
res.statusCode = 304
res.end()
return
send the resource
s.statusCode = 200
s.end('hello, world!')
tion isFresh (req, res) {
turn fresh(req.headers, {
'etag': res.getHeader('ETag'),
'last-modified': res.getHeader('Last-Modified')
er.listen(3000)