@jamesbontempo/typecache

typecache

typecache is a simple TypeScript caching library with ttl support and SQL-inspired syntax.

Install

npm install @jamesbontempo/typecache

Test

npm test

Usage

const { TypeCache } = require("@jamesbontempo/typecache");
const cache = new TypeCache();
cache.insert("key", "value");
cache.update("key", ["new value 1", "new value 2"]);
cache.delete("key");

Constructor

Creates a new TypeCache instance. By default, there is no ttl & all items persist until deleted, or until the cache itself is cleared or destroyed.

Cache properties

count The number of items in the cache.

ttl The default ttl in milliseconds for items inserted into the cache. You can "get" or "set" this value.

Cache methods

keys() Returns an array of the cache keys.

clear() Removes all items from the cache.

Cache item methods

insert(key, value [, ttl]) Inserts an item into the cache. If no ttl is provided the default cache-level ttl is used.

update(key, value) Updates the value of the item in the cache.

remaining(key) Returns the remaining ttl time for the item; that is, how much longer before the item is removed from the cache.

extend(key [, ttl]) Extends the ttl of the item by a number of milliseconds. If no ttl is provided the default cache-level ttl is used (allowing you to basically "bump" the item). If a ttl of Infinity is provided, the ttl is effectively removed.

shorten(key, ttl) Shortens the ttl of the item by a number of milliseconds. If the current ttl is less than the value provided no changes are made because the item would be deleted before the shortened time anyway. If the current ttl is Infinity sets the ttl to the value provided.

delete(key) Deletes the item from the cache.

Cache events

The cache emits events when the insert, update, and delete methods are called. The events have the same corresponding names: insert, update, and delete. They emit objects with information about the related cache items:

{
    key: key name,
    value: key value,
    ttl: ttl,
    added: when the key was added,
    modified: when the key was modified,
    deleted: when the key was deleted
}

insert Emits information about the item inserted.

update Emits information about the updates to an item. Includes before and after objects allowing for comparison.

delete Emits information about the item deleted. Useful to "listen" for ttl expirations.

This allows you to do something like this:

cache.on("delete", item => { doSomethingWith(item); });