Скачать или смотреть How to Fix the Issue of ReactJS Showing Console Messages but Not Updating the UI

Discover the reasons behind ReactJS not updating the UI despite console logs showing the correct data, and learn how to effectively manage component state for dynamic updates.
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This video is based on the question https://stackoverflow.com/q/70727654/ asked by the user 'Mike Ouroumis' ( https://stackoverflow.com/u/17944831/ ) and on the answer https://stackoverflow.com/a/70727787/ provided by the user 'cuongdevjs' ( https://stackoverflow.com/u/7297765/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding the Issue: ReactJS Shows Console Messages but Not in UI

If you're new to ReactJS, you might encounter a frustrating problem: your application logs messages in the console, indicating that your code is working correctly, but it doesn’t reflect those updates in the user interface (UI). This is a common issue, especially when you're trying to dynamically update the DOM based on user interactions, such as clicking a button.

In this post, we'll break down the problem and provide a clear solution to ensure your UI responds correctly to state changes.

The Problem

Consider the following code snippet you might be working with:

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

What’s Wrong?

In this setup:

The currentQuestion variable is treated as a local variable, which is only used within the nextQuestionFunction scope.

By not using React's state management, changes made to currentQuestion do not trigger a re-render of the UI.

As a result, even if console.log displays the updated question, the <p> element in your component remains unchanged.

The Solution: Utilize React State Management

To effectively update the UI in response to state changes, you need to use React's built-in state management feature. Here's how to fix the code step by step:

Step 1: Set Up State

Instead of using a local variable, you should declare currentQuestion as a state variable with React's useState hook. Here’s the updated code:

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

Step 2: Update State on Interaction

You should update the state using the setCurrentQuestion function instead of reassigning the currentQuestion variable. Your nextQuestionFunction should look like this:

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

Step 3: Render the Updated State

In your render method, you’ll now simply reference the state variable, as shown here:

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

Final Code Example

Combining all the changes, your complete code would look like this:

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

Conclusion

Using React's state management is crucial when you want your UI to respond to dynamic changes. By following the above steps, you ensure that your component correctly updates and displays data in the UI, improving both functionality and user experience.

Don’t hesitate to refer back to this guide whenever you run into similar issues in ReactJS. Happy coding!