JavaScript: быстрое случайное индексирование объектных ключей

function generateKeyTracker (keysPropertyName) {
  const set = new Set();
  function defineProperty (target, property, descriptor) {
    target[property] = descriptor.value;

    if (set.has(property)) return true;

    set.add(property);
    target[keysPropertyName].push(property);
    return true;
  }
  function deleteProperty (target, property) {
    delete target[property];
    
    if (!set.delete(property)) return true;

    target[keysPropertyName] = target[keysPropertyName].filter(key => key !== property);
    return true;
  }
  return {defineProperty, deleteProperty};
}

//Create test dictionary
var dict = new Proxy(
  Object.defineProperty({}, '__keys', {
    configurable: true,
    enumerable: false,
    writable: true,
    value: []
  }),
  generateKeyTracker('__keys')
);

for(var i = 0; i < 1e4; i++) {
  var num = Math.random() * 1e6 << 0;
  dict[num] = { Id: num };
}

//Fuzz
const NUM_RUNS = 1e6;
var start = performance.now();
for(var i = 0; i < NUM_RUNS; i++)
  getRandom(dict);
var end = performance.now();

var runTime = end - start;
var timePerCall = (runTime / NUM_RUNS);
console.info(`Total Calls: ${NUM_RUNS}`);
console.info(`Total Runtime: ${runTime} ms`);
console.info(`Time Per Call: ${timePerCall * 1e6} ns`);

function getRandom(dict) {
  var index = Math.random() * dict.__keys.length << 0;
  return dict[dict.__keys[index]];
}