Скачать или смотреть Resolving the Can't perform a React state update on an unmounted component Warning in React Native

Learn how to fix the common React Native warning, `Can't perform a React state update on an unmounted component`, by managing state updates more effectively.
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This video is based on the question https://stackoverflow.com/q/67736083/ asked by the user 'Kanwarjeet Singh' ( https://stackoverflow.com/u/12968130/ ) and on the answer https://stackoverflow.com/a/67736225/ provided by the user 'Drew Reese' ( https://stackoverflow.com/u/8690857/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Warning: Can't perform a React state update on an unmounted component

As a React Native developer, you may have encountered the following warning: "Can't perform a React state update on an unmounted component." This issue often arises when your application navigates away from a screen (unmounting a component) but a state update is still attempted in that component. This situation can indicate potential memory leaks and can disrupt the user experience by leaving behind unnecessary processes. But don’t worry—it’s a common problem with a clear solution!

What Causes This Warning?

The warning typically occurs in scenarios like the following:

You are navigating to a different screen in your application while at the same time trying to update the component state.

As a result, React tries to perform these updates on a component that no longer exists, which leads to the warning.

For instance, if your onSubmit function tries to change the state (like setting a loading indicator) while logging in or transitioning screens, that can prompt this message.

Solution: Updating Your Code to Prevent State Changes on Unmounted Components

Let’s break down how to eliminate the occurrence of this warning from your code.

1. Avoid State Updates After Navigation

You'll want to adjust your onSubmit function so that it no longer attempts to update the state after you navigate to a new screen. Here’s a modified version of your login function:

Updated onSubmit Function

[[See Video to Reveal this Text or Code Snippet]]

2. Keep State Updates Separate From Navigation

Key Adjustments

Return Early After Navigation: In the updated logic, if any condition for navigation is met, the function returns immediately upon calling navigate(). This prevents any subsequent state updates in the promise chain after the navigation has taken place.

State Updates on Error: The catch block updates the state correctly when there's an error, ensuring the loading state is reset. This is crucial to provide feedback to the user regarding the login attempt.

Conclusion

By following these adjustments, you can effectively manage state updates and eliminate the warning about state updates on unmounted components. This not only improves the reliability of your app but also enhances the user experience by avoiding unintended behavior.

If you continue facing issues or have additional questions, feel free to reach out to the React Native community or consult the documentation for more insights.

Happy coding!