A simple LRU cache supporting O(1) set, get and eviction of old keys

$ npm install lru

var LRU = require('lru');

var cache = new LRU(2),
    evicted

cache.on('evict',function(data) { evicted = data });

cache.set('foo', 'bar');
cache.get('foo'); //=> bar

cache.set('foo2', 'bar2');
cache.get('foo2'); //=> bar2

cache.set('foo3', 'bar3'); // => evicted = { key: 'foo', value: 'bar' }
cache.get('foo3');         // => 'bar3'
cache.remove('foo2')       // => 'bar2'
cache.remove('foo4')       // => undefined
cache.length               // => 1

Create a new LRU cache that stores length elements before evicting the least recently used. Optionally you can pass an options map with additional options:

{
  max: maxElementsToStore,
  maxAge: maxAgeInMilliseconds
}

If you pass maxAge items will be evicted if they are older than maxAge when you access them.

Returns: the newly created LRU cache

The number of keys currently in the cache.

Array of all the keys currently in the cache.

Set the value of the key and mark the key as most recently used.

Returns: value

Query the value of the key and mark the key as most recently used.

Returns: value of key if found; undefined otherwise.

Query the value of the key without marking the key as most recently used.

Returns: value of key if found; undefined otherwise.

Remove the value from the cache.

Returns: value of key if found; undefined otherwise.

Respond to events. Currently only the evict event is implemented. When a key is evicted, the callback is executed with an associative array containing the evicted key: {key: key, value: value}.

A big thanks to Dusty Leary who finished the library.

MIT