quick-lru

Simple “Least Recently Used” (LRU) cache

Useful when you need to cache something and limit memory usage.

Inspired by the hashlru algorithm, but instead uses Map to support keys of any type, not just strings, and values can be undefined.

Install

$ npm install quick-lru

Usage

const QuickLRU = require('quick-lru');

const lru = new QuickLRU({maxSize: 1000});

lru.set('🦄', '🌈');

lru.has('🦄');
//=> true

lru.get('🦄');
//=> '🌈'

API

new QuickLRU(options?)

Returns a new instance.

options

Type: object

maxSize

Required
Type: number

The maximum number of items before evicting the least recently used items.

onEviction

Optional
Type: (key, value) => void

Called right before an item is evicted from the cache.

Useful for side effects or for items like object URLs that need explicit cleanup (revokeObjectURL).

Instance

The instance is iterable so you can use it directly in a for…of loop.

Both key and value can be of any type.

.set(key, value)

Set an item. Returns the instance.

.get(key)

Get an item.

.has(key)

Check if an item exists.

.peek(key)

Get an item without marking it as recently used.

.delete(key)

Delete an item.

Returns true if the item is removed or false if the item doesn't exist.

.clear()

Delete all items.

.keys()

Iterable for all the keys.

.values()

Iterable for all the values.

.size

The stored item count.