Sizable Hash with expiring keys for storing objects in memory in Node.js. Oldest object will be removed from the hash once the limit is reached.

l1cache.js

//created by Rick Crawford - https://github.com/rickcrawford

var _ = require("underscore"),
    bunyan = require('bunyan');

var log = bunyan.createLogger({
    name: "test",
    stream: process.stdout,
    level: 'debug'
});

function L1(max) {
    this.values = {};
    this.keys = [];
    this.maxSize = max || 100;
};

L1.prototype.set = function(key, value, ttl) {
    log.debug('setL1', key, value, ttl);

    //remove the key if it exists...
    this.delete(key);

    //set the values
    this.values[key] = value;
    this.keys.push(key);

    //only resize if necessary
    if (this.keys.length > this.maxSize) {
        log.debug('current keys:', this.keys);
        //remove oldest key...
        var k = this.keys.shift();
        this.delete(k);
        log.debug('deleted key: %s from L1', k);
    }

    if (ttl && ttl > 0) {
        log.debug('setting timeout %d for key %s', ttl, key);
        var that = this;
        setTimeout(function() {
            log.debug('expiring L1 key %s', key);
            that.delete(key);
        }, ttl);
    }
};

L1.prototype.size = function() {
    return this.values.length;
}

L1.prototype.delete = function(key) {
    delete this.values[key];
    this.keys = _.without(this.keys, key);

    this.length = this.values.length;
};

L1.prototype.get = function(key) {
    return this.values[key];
};

L1.prototype.keys = function() {
    return this.keys;
}

L1.prototype.toString = function() {
    return JSON.stringify(this.values);
};

var l1cache = new L1();