Bug: React 18 (18.2.0) skips renders in Safari even when props change about react

[BryanChrisBrown]

Also hitting this issue, safari version 17.1

[Hyodori04]

If use dangerouslySetInnerHTML. It works

[gaearon]

Would you mind turning this into two CodeSandbox'es? Thanks!

[evanbernstein]

@gaearon I created this CodeSandbox with the code. Unfortunately, the issue does not reproduce in CodeSandbox. You can certainly view the code. Is there any chance you could test out the repo that I created on your machine?

Thanks.

[evanbernstein]

@gaearon My best guess is that everything runs just a bit slower in CodeSandbox and thus the renders don't get skipped, at least on my Intel Mac. You are probably a much better expert than I am.

I did just try the CodeSandbox implementation on an m1 mac, and it was not reproducible there.

[nicolawebdev]

True, tested on my MacBook (M1 Pro) with Safari 16.5.

[draysams]

Test on MacBook (M2 Pro) with Safari 16.6. Can confirm I'm facing this issue as well.

[evanbernstein]

With the release of macOS Sonoma imminent, I updates the packages in my linked project and tested in the latest Safari.

info Direct dependencies
├─ @types/[email protected]
├─ @types/[email protected]
└─ @types/[email protected]
info All dependencies
├─ @types/[email protected]
├─ @types/[email protected]
├─ @types/[email protected]
├─ @types/[email protected]
├─ @types/[email protected]
└─ [email protected]

With these updates this is still reproducible with Safari Version 17.0 (19616.1.27.111.16).

[brunofin]

we are also affected by this bug on nextjs and react 18.2.0

[fabiancarlos]

Its dont render nothing, cant find why... but, i fixed temporarly on Safari mobile, with my iPhone, opening:
Configuration > Safari > Advanced > Experimental Features > than activate all.

So, now renders, but, its just too absurd to ask for any user to do this.

[timwuhaotian]

Same happens for iOS, v11.2

[ajbura]

It happens to me as well in safari.

But I think problem is with how batch state update breaks declarative set state notion.
For example

export enum AsyncStatus {
  Idle = 'idle',
  Loading = 'loading',
  Success = 'success',
  Error = 'error',
}

export type AsyncIdle = {
  status: AsyncStatus.Idle;
};

export type AsyncLoading = {
  status: AsyncStatus.Loading;
};

export type AsyncSuccess<D> = {
  status: AsyncStatus.Success;
  data: D;
};

export type AsyncError<E = unknown> = {
  status: AsyncStatus.Error;
  error: E;
};

export type AsyncState<D, E = unknown> = AsyncIdle | AsyncLoading | AsyncSuccess<D> | AsyncError<E>;

AsyncState is state of my useAsyncCallback hook. so in safari fetch request resolves so fast(~8ms when browser has it's result cached) that react batch AsyncLoading and AsyncSuccess state, and in component A where this hook used, state update from prev AsyncSuccess to new AsyncSuccess state.

So in that component A i render a child only when result is AsyncSuccess and based on that contract that child component should unmount and re-mount when the fetch request happen as I explicitly declare AyncLoading before fetch happen and AsyncSuccess got set.

And because react skip that state, my child component (screenshot below) doesn't go though mount unmount cycle.
Child component:

And in my child component code which depend on the mount-unmount cycle doesn't run which result in in missing UI update:

if (state.status === AsyncStatus.Idle) load();

Now i can run that load() callback in useEffect to fix this or wrap the set AyncLoading state in flushSync

but issue is actually with the how batch update breaks react declarative nature as i explicitly declare the state to be updated. I think immediate update is the correct declarative nature and batch update have to be optional and declarative with API like:

batchUpdates(() => {
//multiple set state calls
})

For more: React provides a declarative way to manipulate the UI: https://react.dev/learn/reacting-to-input-with-state#how-declarative-ui-compares-to-imperative

[ajbura]

@evanbernstein same ^^^ is happening with you

import React from "react";

interface LogProp {
  message: string;
  number: number;
  title: string;
  subtitle: string;
}
export const LogWithState: React.FC<{ log: LogProp }> = ({ log }) => {
  const { message, number, title, subtitle } = log;
  const [prevMessages, setMessages] = React.useState<string[]>([]);
  const [prevNumber, setNumber] = React.useState(-1);
  if (number !== prevNumber) {
    const newMessages = prevMessages.concat(message);
    setMessages(newMessages);
    setNumber(number);
  }
  return (
    <>
      <h2>{title}</h2>
      <h3>{subtitle}</h3>
      <div>
        {prevMessages.map((message, i) => (
          <div key={i}>{message}</div>
        ))}
      </div>
    </>
  );
};

your setMessages(newMessages) are getting ignored by batchUpdate and it only set the last call with prevMessage and last message

[ajbura]

Now i can run that load() callback in useEffect to fix this or wrap the set AyncLoading state in flushSync

i was wrong about calling load() in useEffect, I mean this is something I should do i.e calling load again if one of load dependencies changes. but that batch update makes the data problem more worse as now context data from component A and context data produces by child AuthFlowLoader component, in combination serve as wrong data for react tree down the line until that load function resolves to new data.

So, overall I have to do:

flushSync(() => {
  setState({
    status: AsyncStatus.Loading,
  });
});

before resolving async callback.
And API flushSync doesn't make sense to me much, because I have to tell it to do what it suppose to do at first place, and now i am more concern about possible happening of situation like this through out the whole app.

Edited:

Warning: flushSync was called from inside a lifecycle method. React cannot flush when React is already rendering. Consider moving this call to a scheduler task or micro task.

queueMicrotask(() => {
  flushSync(() => {
    setState({
      status: AsyncStatus.Loading,
    });
  });
});

👀

[navyblue21]

Same happens for iOS v14.4, React 18.2.0

[github-actions]

This issue has been automatically marked as stale. If this issue is still affecting you, please leave any comment (for example, "bump"), and we'll keep it open. We are sorry that we haven't been able to prioritize it yet. If you have any new additional information, please include it with your comment!

[evanbernstein]

bump