其他可变处理器

function deleteProperty(target: object, key: string | symbol): boolean {
  const hadKey = hasOwn(target, key);
  const oldValue = (target as any)[key];
  const result = Reflect.deleteProperty(target, key);
  if (result && hadKey) {
    trigger(target, TriggerOpTypes.DELETE, key, undefined, oldValue);
  }
  return result;
}

function has(target: object, key: string | symbol): boolean {
  const result = Reflect.has(target, key);
  track(target, TrackOpTypes.HAS, key);
  return result;
}

function ownKeys(target: object): (string | number | symbol)[] {
  track(target, TrackOpTypes.ITERATE, ITERATE_KEY);
  return Reflect.ownKeys(target);
}

export const mutableHandlers: ProxyHandler<object> = {
  get,
  set,
  deleteProperty,
  has,
  ownKeys,
};

可见has，ownKeys是读取操作，所以调用跟踪，而delete则显然是修改操作，所以进行trigger