Simple LRU cache in JavaScript

The implementation is inspired by node-lru-cache by Isaac Schlueter. The motivation of this project is to provide Object.create fallback in order to work on IE8.

Installation

With npm

$ npm install simple-lru

With Component

$ component install smagch/simple-lru

With Bower

$ bower install simple-lru

Or download tarball.

Examples

You can set any value with a string key.

var cache = new SimpleLRU(3);
cache.set('a', 'A');
cache.set('b', {name: 'smagch'});
cache.set('c', 1000);
var a = cache.get('a'); // a = 'A'
var b = cache.get('b'); // b = {name: 'smagch'}
var c = cache.get('c'); // c = 1000

It removes cache items automatically when total length get out of max.

var cache = new SimpleLRU(3);
cache.set('a', 'A');
cache.set('b', 'B');
cache.set('c', 'C');
cache.set('d', 'D');
var a = cache.get('a'); // a = undefined;
var b = cache.get('b'); // b = 'B'
var c = cache.get('c'); // c = 'C'
var d = cache.get('d'); // d = 'D'
var keys = cache.keys(); // keys = ['b', 'c', 'd']

Since it's using LRU cache algorithm, it removes the least recently used item.

var cache = new SimpleLRU(3);
cache.set('a', 'A');
cache.set('b', 'B');
cache.set('c', 'C');
// Calling `get` with 'a', 'a' is the most recently used item.
var a = cache.get('a'); // a = 'A'
var keys = cache.keys(); // keys = ['b', 'c', 'a']
 
cache.set('d', 'D');
a = cache.get('a'); // a = 'A'
var b = cache.get('b'); // b = undefined
var c = cache.get('c'); // c = 'C'
var d = cache.get('d'); // d = 'D'

API

new SimpleLRU(max)

Create a new SimpleLRU instance with given max cache number. max option should be a positive number.

SimpleLRU#set(key, value)

Set a new cache with given key and value.

SimpleLRU#get(key)

Get a cache by key.

SimpleLRU#peek(key)

Get a cache without updating recently used order.

SimpleLRU#del(key)

Delete a cache by key.

SimpleLRU#has(key)

See if it has a cache with given key.

SimpleLRU#length()

Return total number of cache items.

SimpleLRU#reset()

Clear all stored cache.

SimpleLRU#keys()

Return an Array of existing cache keys in least recently used order. The most recently used cache item will be the last.

SimpleLRU#max([max])

Getter|Setter of max option. Get a max option if it has no argument. And change max option with an argument. It will trim cache when new max option is smaller than its length.

License

MIT