Documentation for sync option in derive()

[hastebrot]

I wondered what the sync option in derive() does. I looked into the source code and found that with sync: true the proxy value updates will be synced immediately.

if (notifyInSync) {
  unmarkPending(sourceObject)
} else {
  subscription.p = Promise.resolve().then(() => {
    delete subscription.p // promise
    unmarkPending(sourceObject)
  })
}

I wonder if there can be some documentation about this option. For my unittests I had to use await tick(); before I can make assertions on the changed proxy/derive values, before I found the sync option which allows to skip this step.

export const tick = () => {
  // schedules a function to be executed in the next iteration of the event loop,
  // after the current event loop cycle completes.
  return new Promise((resolve) => {
    setImmediate(resolve);
  });
};

[dai-shi]

First of all, you are welcome to open a PR to improve docs. It has been improved like that way.

sync: true in derive() is notifyInSync for subscribe. It's technically how it works. However, usage-wise, sync: true behaves somewhat unexpectedly. So, I'm not sure if it's something useful for many cases. await tick() seems correct in your case.