Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

Dispatch more than once in non-batched update cause incorrect result with `useSelector`

See original GitHub issue

Do you want to request a feature or report a bug?

Report a bug.

What is the current behavior?

I’v created a reproducing repo here https://github.com/malash/react-redux-issue-ref/blob/master/reduxBug.js

This repo use both react-redux and react-native.

<Button
  title="[BUG] Click Me (setTimeout)"
  onPress={() => {
    setTimeout(() => {
      dispatch({type: 'NOOP'});
      dispatch({type: 'TOGGLE'});
    }, 0);
  }}
/>

When using setTimeout’s callback to dispatch multi times, the useSelector return incorrect value. The reason why I use setTimeout is to ensure these dispatch calling are non-batched.

const selector = state => ({
	bool: state.bool,
});

const ReduxBugParent = () => {
  const {bool} = useSelector(selector);
  // ...
  <Text>bool from useSelector is {JSON.stringify(bool)}</Text>
  <Text>bool from store.getState is {JSON.stringify(boolFromStore)}</Text>
}

After click the button different selector result are shown. the bool are always different with boolFromStore.

Screen Recording 2019-10-29 at 11 05 55 PM

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn’t have dependencies other than React. Paste the link to a CodeSandbox (https://codesandbox.io/s/new) or RN Snack (https://snack.expo.io/) example below:

Clone the repo https://github.com/malash/react-redux-issue-ref
Install React Native CLI
Run react-native run-ios
Click buttons and see rendered values.

What is the expected behavior?

This bug can only reproduce on non-web environment, maybe it is related to https://github.com/reduxjs/react-redux/issues/1436

I believe it should works on React Native as well as React DOM.

Which versions of React, ReactDOM/React Native, Redux, and React Redux are you using? Which browser and OS are affected by this issue? Did this work in previous versions of React Redux?

react@16.9.0 react-native@0.61.2 react-redux@7.1.1 redux@4.0.4

@byunicorn