This is an LRU Cache implementation using Map as the native Map guarantees the order of the of the [key, value] pairs to be maintained in the insertion order.

The LRU allows to use anything as key/value just like Map, and it follows the same interface as a Map, with the addition of peek method and maxSize property.

import LRU from "https://deno.land/x/lru_store/mod.ts";

npm install --save @denox/lru_store

import LRU from "@denox/lru_store";

The first argument is maxSize and it is required, the second one is entries and it is optional, allowing prepopulating the cache.

const lru = new LRU(100); // Creates an empty LRU Cache with 100 entries capacity
const lruWithData = new LRU(100, [
	["key1", "value1"],
	["key2", "value2"],
]); // Creates an LRU Cache with 2 entries and 100 entries capacity

Add a key/value pair to the cache. If the cache will exceed capacity, it will evict the oldest key/value pair.

lru.set("key", "value");

Retrieve a value from the cache based on the keys, it will return undefined if the key is not found.

lru.get("key");

Retrieve the value from the cache based on the key, similar with get but without changing the priority of the queue.

// Same behavior as get but without moving the key/value to the end of the eviction queue
lru.peek("key");

Check if a key is inside the LRU, returning true if found or false if not.

lru.has("key");

Evict the key/value pair based on key, returning true if found or false if not.

lru.delete("key");

Evict everything from the cache, leaving the LRU empty.

lru.clear();

Get the current size of the LRU.

lru.size; // Number

Get the set capacity of the LRU, size should never exceed maxSize.

lru.maxSize; // Number

Get the iterators for keys, values or entries in the eviction order.

Array.from(lru.keys()); // [key1, key2, ...]
Array.from(lru.values()); // [value1, value2, ...]
Array.from(lru.entries()); // [[key1, value1], [key2, value2], ...]

Iterate over the LRU entries in the eviction order.

lru.forEach((value, key, lru) => {
	//...
});

MIT