123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137 |
-
-
- 'use strict'
-
-
-
- var CACHE_CONTROL_NO_CACHE_REGEXP = /(?:^|,)\s*?no-cache\s*?(?:,|$)/
-
-
-
- module.exports = fresh
-
-
-
- function fresh (reqHeaders, resHeaders) {
-
- var modifiedSince = reqHeaders['if-modified-since']
- var noneMatch = reqHeaders['if-none-match']
-
-
- if (!modifiedSince && !noneMatch) {
- return false
- }
-
-
-
-
- var cacheControl = reqHeaders['cache-control']
- if (cacheControl && CACHE_CONTROL_NO_CACHE_REGEXP.test(cacheControl)) {
- return false
- }
-
-
- if (noneMatch && noneMatch !== '*') {
- var etag = resHeaders['etag']
-
- if (!etag) {
- return false
- }
-
- var etagStale = true
- var matches = parseTokenList(noneMatch)
- for (var i = 0; i < matches.length; i++) {
- var match = matches[i]
- if (match === etag || match === 'W/' + etag || 'W/' + match === etag) {
- etagStale = false
- break
- }
- }
-
- if (etagStale) {
- return false
- }
- }
-
-
- if (modifiedSince) {
- var lastModified = resHeaders['last-modified']
- var modifiedStale = !lastModified || !(parseHttpDate(lastModified) <= parseHttpDate(modifiedSince))
-
- if (modifiedStale) {
- return false
- }
- }
-
- return true
- }
-
-
-
- function parseHttpDate (date) {
- var timestamp = date && Date.parse(date)
-
-
- return typeof timestamp === 'number'
- ? timestamp
- : NaN
- }
-
-
-
- function parseTokenList (str) {
- var end = 0
- var list = []
- var start = 0
-
-
- for (var i = 0, len = str.length; i < len; i++) {
- switch (str.charCodeAt(i)) {
- case 0x20:
- if (start === end) {
- start = end = i + 1
- }
- break
- case 0x2c:
- list.push(str.substring(start, end))
- start = end = i + 1
- break
- default:
- end = i + 1
- break
- }
- }
-
-
- list.push(str.substring(start, end))
-
- return list
- }
|