expiring map, different style

expire.js

// opts = { timeout: 60 }
function ExpiringMap(opts) {
  var self = {}
    , map = {}
    , activeKeys = {
      // key: clearTimeout
    }
    , noop = function() {};
    ;

  self.timeout = opts.timeout * 1000 || 60 * 1000;

  // k, v [, timeout, cb]
  self.set = function(k, v, timeout, cb) {
    if (!cb && typeof timeout === 'function') {
      cb = timeout;
      timeout = undefined;
    }
    cb = cb || noop;
    timeout = timeout * 1000 || self.timeout;

    map[k] = v;
    activeKeys[k] = setTimeout(function() {
      self.remove(k);
      cb(k, v, timeout / 1000);
    }, timeout);
  };

  self.get = function(k) {
    return map[k]; // returns undefined if not contained
  };
  self.remove = function(k) {
    clearTimeout(activeKeys[k]);
    delete activeKeys[k];
    delete map[k];
  };

  self.contains = function(k) {
    return (k in activeKeys);
  };

  self.getKeyList = function() {
    var list = [];
    for (k in activeKeys) {
      list.push(k);
    }
    return list;
  };

  return self;

};

var exports = exports || {};
exports.ExpiringMap = ExpiringMap;

//
// Test it
//
if (!module.parent) {
  var map = new ExpiringMap({ timeout: 1 });

  map.set('ohai', 'dude.', function(k, v) {
    console.log('sayin', k, v);
  });

  console.log("map.contains('ohai') =",map.contains('ohai'));
  console.log("map.get('ohai') =",map.get('ohai'));
  
  map.set('glug', {a: 2}, 5, function(k, v, t) {
    console.log(k,'=',v,'expired after non-default timeout of',t,'s');
  });

  map.set('deletemefast', 'please', function() {
    console.log('you were not fast enough!');
  });
  
  map.remove('deletemefast');
  console.log("map.contains('deletemefast') =", map.contains('deletemefast'));

}