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Learn how to fix excessive re-renders in React when using the `useReducer` hook. This step-by-step guide will help you understand common pitfalls, with easy-to-follow examples.
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This video is based on the question https://stackoverflow.com/q/64052123/ asked by the user 'Lyes' ( https://stackoverflow.com/u/9529376/ ) and on the answer https://stackoverflow.com/a/64052209/ provided by the user 'Viet Dinh' ( https://stackoverflow.com/u/10661409/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Resolving Too Many Re-renders in React with the useReducer Hook

As developers, we always aim for a seamless and efficient user experience. However, sometimes we encounter unexpected behavior in our applications. One such problem arises when using the useReducer hook in React: the dreaded "too many re-renders" issue. In this post, we'll explore the root cause of this problem and provide a clear, step-by-step solution.

Understanding the Problem

Imagine you've implemented a simple state management system using the useReducer hook to manage the scores in a game application. However, you notice that when the component renders, it triggers multiple re-renders unexpectedly. This can be frustrating, especially when you believe your dispatch calls are setup correctly for user interactions like button clicks.

The Original Code

Here’s a snippet of the original code that might cause the issue:

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

The Mistake

In the code above, the line that triggers the dispatch function is directly invoked in the onClick prop of the Button component:

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

This pattern results in the dispatch function being called immediately upon render, rather than waiting for a click event. This is the primary reason for excessive re-renders.

The Solution

To properly handle button clicks and prevent unnecessary re-renders, you need to modify how you call the dispatch function. Instead of calling it directly, wrap it in an arrow function. Here’s the updated code:

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

Updated Code Implementation

Here’s how the full component looks with the correct implementation:

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

Conclusion

Understanding why excessive re-renders happen in your React applications when using hooks like useReducer is crucial for building efficient and responsive interfaces. By simply wrapping the dispatch calls in an arrow function, you can ensure that the state updates only when intended, during user interactions.

Keep this implementation in mind as you develop your React applications, and you'll manage state effectively without encountering the frustrating issue of too many renders. Happy coding!