51 lines
1.7 KiB
JavaScript
51 lines
1.7 KiB
JavaScript
const CACHE_CONTROL_NO_CACHE_REGEXP = /(?:^|,)\s*?no-cache\s*?(?:,|$)/;
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const compareETags = (etag, str) => str === etag || str === `W/${etag}` || `W/${str}` === etag;
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function isStale(etag, noneMatch) {
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let start = 0;
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let end = 0;
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for (let i = 0, len = noneMatch.length; i < len; i++) {
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switch (noneMatch.charCodeAt(i)) {
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case 0x20 /* */:
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if (start === end)
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start = end = i + 1;
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break;
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case 0x2c /* , */:
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if (compareETags(etag, noneMatch.substring(start, end)))
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return false;
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start = end = i + 1;
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break;
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default:
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end = i + 1;
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break;
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}
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}
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if (compareETags(etag, noneMatch.substring(start, end)))
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return false;
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return true;
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}
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/**
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* Check freshness of the response using request and response headers.
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*/
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export function fresh(reqHeaders, resHeaders) {
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const modifiedSince = reqHeaders['if-modified-since'];
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const noneMatch = reqHeaders['if-none-match'];
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if (!modifiedSince && !noneMatch)
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return false;
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const cacheControl = reqHeaders['cache-control'];
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if (cacheControl && CACHE_CONTROL_NO_CACHE_REGEXP.test(cacheControl))
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return false;
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// if-none-match
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if (noneMatch && noneMatch !== '*') {
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const etag = resHeaders.etag;
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if (!etag || isStale(etag, noneMatch))
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return false;
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}
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// if-modified-since
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if (modifiedSince) {
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const lastModified = resHeaders['last-modified'];
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if (!lastModified || !(Date.parse(lastModified) <= Date.parse(modifiedSince)))
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return false;
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}
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return true;
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}
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//# sourceMappingURL=fresh.js.map
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