quick-lru
Advanced tools
Package description
The quick-lru package is a fast and efficient least-recently-used (LRU) cache implementation in JavaScript. It is designed to store a limited amount of items and evict the least-recently-used items once the limit is reached. This package is useful for caching results, reducing the number of expensive operations (like I/O), and improving application performance.
Set and Get Items
This feature allows you to set and retrieve items from the cache using the 'set' and 'get' methods. The 'maxSize' option specifies the maximum number of items the cache can hold.
{"const QuickLRU = require('quick-lru');
const lru = new QuickLRU({maxSize: 1000});
lru.set('key', 'value');
const value = lru.get('key'); // 'value'"}Cache Eviction
This feature automatically evicts the least-recently-used items when the cache reaches its maximum size. In this example, after adding three items to a cache with a maxSize of 2, the first item is evicted.
{"const QuickLRU = require('quick-lru');
const lru = new QuickLRU({maxSize: 2});
lru.set('a', 1);
lru.set('b', 2);
lru.set('c', 3);
// At this point, 'a' is evicted because it is the least recently used item"}Cache Deletion and Clearing
This feature allows you to delete individual items or clear the entire cache. The 'delete' method removes a specific item, and the 'clear' method removes all items.
{"const QuickLRU = require('quick-lru');
const lru = new QuickLRU({maxSize: 1000});
lru.set('key', 'value');
lru.delete('key'); // Removes 'key' from the cache
lru.clear(); // Removes all items from the cache"}Cache Size and Existence Check
This feature provides methods to check the current size of the cache and whether a specific key exists in the cache. The 'size' property gives the number of items in the cache, and the 'has' method checks for the existence of a key.
{"const QuickLRU = require('quick-lru');
const lru = new QuickLRU({maxSize: 1000});
lru.set('key', 'value');
const size = lru.size; // 1
const hasKey = lru.has('key'); // true"}lru-cache is another popular LRU cache implementation. It offers a similar set of features to quick-lru, such as set, get, eviction of old items, and item deletion. However, it has additional features like item expiration times, which quick-lru does not support.
node-cache is a simple caching module with set, get, and delete methods, similar to quick-lru. It supports TTL (time to live) for cache items and can be used as a plain key-value store. It is not strictly an LRU cache, but it provides similar caching capabilities.
tiny-lru is a minimal LRU cache implementation that is small in size. It provides basic LRU caching functionality like quick-lru but is designed to have a smaller footprint, making it suitable for environments where package size is a concern.
Readme
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.
$ npm install quick-lru
import QuickLRU from 'quick-lru';
const lru = new QuickLRU({maxSize: 1000});
lru.set('🦄', '🌈');
lru.has('🦄');
//=> true
lru.get('🦄');
//=> '🌈'
Returns a new instance.
It's a Map subclass.
Type: object
Required
Type: number
The maximum number of items before evicting the least recently used items.
Type: number
Default: Infinity
The maximum number of milliseconds an item should remain in cache. By default maxAge will be Infinity, which means that items will never expire.
Lazy expiration happens upon the next write or read call.
Individual expiration of an item can be specified by the set(key, value, options) method.
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).
The instance is an Iterable of [key, value] pairs so you can use it directly in a for…of loop.
Both key and value can be of any type.
Set an item. Returns the instance.
Individual expiration of an item can be specified with the maxAge option. If not specified, the global maxAge value will be used in case it is specified on the constructor, otherwise the item will never expire.
Get an item.
Check if an item exists.
Get an item without marking it as recently used.
Delete an item.
Returns true if the item is removed or false if the item doesn't exist.
Delete all items.
Update the maxSize, discarding items as necessary. Insertion order is mostly preserved, though this is not a strong guarantee.
Useful for on-the-fly tuning of cache sizes in live systems.
Iterable for all the keys.
Iterable for all the values.
Iterable for all entries, starting with the oldest (ascending in recency).
Iterable for all entries, starting with the newest (descending in recency).
Iterable for all entries, starting with the newest (ascending in recency).
This method exists for Map compatibility. Prefer .entriesAscending() instead.
Loop over entries calling the callbackFunction for each entry (ascending in recency).
This method exists for Map compatibility. Prefer .entriesAscending() instead.
The stored item count.
FAQs
Simple “Least Recently Used” (LRU) cache
The npm package quick-lru receives a total of 14,233,152 weekly downloads. As such, quick-lru popularity was classified as popular.
We found that quick-lru demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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