Cacheability NPM

cacheability

A utility class to parse, store and print http cache headers.

Installation

npm add cacheability

Documentation

Initialization

The constructor takes either a Headers instance, object literal of header key/values, cache-control header field value or Cacheability metadata object, parses it, if required, and then stores the result on the Cacheability instance's metadata property.

import { Cacheability } from "cacheability";

const headers = new Headers({
  "cache-control": "public, max-age=60",
  "content-type": "application/json",
  "etag": "33a64df551425fcc55e4d42a148795d9f25f89d4",
});

const cacheability = new Cacheability({ headers });

const { cacheControl, etag, ttl } = cacheability.metadata;
// cacheControl is { maxAge: 60, public: true }
// etag is 33a64df551425fcc55e4d42a148795d9f25f89d4
// ttl is 1516060712991 if Date.now is 1516060501948

Properties

metadata

The property holds the Cacheability instance's parsed cache headers data, including cache control directives, etag, and a derived TTL timestamp.

Methods

checkTTL

The method checks whether the TTL timestamp stored in the Cacheability instance is still valid, by comparing it to the current timestamp.

const cacheability = new Cacheability({ cacheControl: "public, max-age=3" });

// One second elapses...

const isValid = cacheability.checkTTL();
// isValid is true

// Three seconds elapse...

const isStillValid = cacheability.checkTTL();
// isStillValid is false

printCacheControl

The method prints a cache-control header field value based on the Cacheability instance's metadata. The max-age and/or s-maxage are derived from the TTL stored in the metadata.

const cacheability = new Cacheability({ cacheControl: "public, max-age=60, s-maxage=60" });

// Five seconds elapse...

const cacheControl = cacheability.printCacheControl();
// cacheControl is "public, max-age=55, s-maxage=55"