Скачать или смотреть Updating a Loading State in React with Every Iteration of a Map Loop

Discover how to effectively update a loading percentage in React during a computation-heavy map loop process. Learn useful coding techniques and tips!
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How to Update a Loading State in React During Heavy Computation

When building React applications, efficiently managing state updates can often be a challenge—especially during heavy computations. One common scenario developers face is updating the user interface with progress indicators as computations take place. This guide will show you how to update a loading state using React hooks, specifically during iterations of a map function.

The Problem

You may find yourself in a situation where you need to perform a complex calculation using a loop, such as a map function, while also updating the DOM to reflect the progress of that computation. For instance, you might need to compute loading percentages continuously.

In this particular case, the goal is to update a loading percentage variable in the DOM while calculating animation frames based on a series of moves from a string representation (like a chess game).

Example Scenario

Suppose you have a method, getAnimationFrames(), that computes animation frames based on game moves. The challenge is to ensure that as this method runs, an accompanying loading percentage is also displayed on the screen. Your code might look like this:

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You want to display loadingPercentage in your component like this:

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However, simply trying to update the state with useState isn't yielding the desired results.

The Solution

To achieve a dynamic loading state update in React, we can adopt a method that leverages both useState and a callback mechanism. Here's a step-by-step breakdown of how to implement this effectively.

Step 1: State Management

First, you need to create a state variable to manage your loading percentage and animation frames. This will allow your component to re-render when the loading percentage changes.

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Step 2: Incorporate the Heavy Computation

Next, use the useEffect hook to initiate your heavy computation. You will call a function responsible for the animation frames while also passing in a way to update the loading percentage:

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Step 3: Define the Heavy Computation Function

Within this function, you can iterate over the computation while updating the loading percentage using the setFrames function. This will ensure your state is synchronized and reflects the progress in the DOM.

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Now, on every 10 iterations of the loop, your loadingPercentage will update, which will consequently update the DOM.

Step 4: Render the Loading Percentage

Finally, ensure that your JSX correctly renders the loading percentage:

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Conclusion

By following this structured approach, you can effectively manage heavy computations in React while updating the loading state in real-time. This will enhance user experience by providing instant feedback during processing, making your application feel more responsive and interactive.

Feel free to play around with the frequency of updates and computations to best suit your application needs. Happy coding!