zone-simulate.js

const Zone = {
  _currentZone: {},
  get current() {
    return {
      ...this._currentZone,
      fork: (zone) => {
        this._currentZone = {
          ...this._currentZone,
          ...zone,
        };
        return this;
      },
      set: (key, value) => {
        this._currentZone[key] = value;
      },
    };
  },
};

(() => {
  const _setTimeout = global.setTimeout;
  global.setTimeout = (cb, timeout, ...args) => {
    const _currentZone = Zone._currentZone;
    _setTimeout(() => {
      const __after = Zone._currentZone;
      Zone._currentZone = _currentZone;
      cb(...args);
      Zone._currentZone = __after;
    }, timeout);
  };
})();

for (let i = 0; i < 10; i++) {
  const value = Math.floor(Math.random() * 100);
  console.log(i, value);
  Zone.current.fork({ i, value });
  setTimeout(() => {
    console.log(Zone.current.i, Zone.current.value);
  }, value);
}