lru_cache_impl.js

function LRUCache(capacity, init)
{
  var capacity = capacity;
  var data = init || {};
  var timestamps = {};

  var getTimestamp = function()
  {
    var time = Date.now();

    while(time === Date.now());
    return Date.now();
  };

  var findLRU = function()
  {
    var keys = Object.keys(timestamps);

    return keys
      .reduce(function(acc, x)
      {
        if (timestamps[x] < acc.time)
        {
          return {key: x, time: timestamps[x]} ;
        } else { return acc;}
    }, {key: keys[0], time: timestamps[keys[0]] });
  };

  var cache = function(key, val)
  {
    if (!key) return data;
    if (key && val)
    {
      setCache(key, val);
    }

    if (this.size > this.capacity)
    {
      var lruItem = findLRU();
      deleteCache(lruItem.key);
    }

    return this;
  }.bind(this);