# `@arcjet/cache`

[Arcjet][arcjet] cache interface and implementations. - [npm package (`@arcjet/cache`)](https://www.npmjs.com/package/@arcjet/cache) - [GitHub source code (`cache/` in `arcjet/arcjet-js`)](https://github.com/arcjet/arcjet-js/tree/main/cache) ## What is this? This is an internal utility to help us cache some things in memory. ## When should I use this? This is an internal Arcjet package not designed for public use. See our [_Get started_ guide][arcjet-get-started] for how to use Arcjet in your application. ## Install This package is ESM only. Install with npm in Node.js: ```sh npm install @arcjet/cache ``` ## Use ```ts import { setTimeout } from "node:timers/promises"; import { MemoryCache } from "@arcjet/cache"; const cache = new MemoryCache(); cache.set("namespace", "key", "value", 2); console.log(await cache.get("namespace", "key")); // => [ 'value', 2 ] await setTimeout(2001); console.log(await cache.get("namespace", "key")); // => [ undefined, 0 ] ``` ## API ### `MemoryCache#constructor()` Instantiate the `MemoryCache` using `new MemoryCache()` without any arguments. ### `MemoryCache#get(namespace: string, key: string): Promise<[T | undefined, number]>` Attempts to retrieve a value from the cache. If a value exists, it will be returned with the remaining time-to-live (in seconds). Non-string arguments will cause the returned promise to reject. ### `MemoryCache#set(namespace: string, key: string, value: T, ttl: number): void` Makes a best attempt at storing the value provided until the time-to-live specified. Non-string arguments will cause the function to throw. ## License [Apache License, Version 2.0][apache-license] © [Arcjet Labs, Inc.][arcjet] [arcjet]: https://arcjet.com [arcjet-get-started]: https://docs.arcjet.com/get-started [apache-license]: http://www.apache.org/licenses/LICENSE-2.0