Скачать или смотреть How to Display New Comments Instantly in React with useEffect and useState

Learn how to make your comments update immediately in React when using `useEffect` and `useState`. This post discusses common pitfalls and offers effective solutions.
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This video is based on the question https://stackoverflow.com/q/63755728/ asked by the user '장동균' ( https://stackoverflow.com/u/14071532/ ) and on the answer https://stackoverflow.com/a/63756186/ provided by the user 'Tùng Nguyễn' ( https://stackoverflow.com/u/4635041/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Display New Comments Instantly in React with useEffect and useState

In the world of web applications, presenting real-time information is a crucial component to enhance user experience. One common scenario developers face is ensuring that newly added comments on a post appear immediately without requiring a page reload. If you’re using React and are stuck with the issue of comments not displaying until the page reloads, this guide is for you.

Understanding the Problem

The problem arises when you submit a new comment. While the data is successfully sent to the backend and returned as a response, the original state in your component does not update automatically. As a result, users must refresh the page to see their new comment, which is not an ideal user experience.

Code Overview

In the shared code snippet, the aim is to update the posts array with new comments whenever a new one is submitted. Here is the relevant part from the original code:

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

Unfortunately, this attempt does not yield the desired outcome. Let’s break down the solution to fix this issue step by step.

Solution: Updating Comments in React State

Identifying the Issue

The core of the problem lies in this part of your code: setPosts({...posts,posts[i].comments:response.data.comments,});. Since posts is an array and not an object, the way you are trying to update it won't work. Instead, you'll need to adopt a different approach to ensure that both the current data is preserved and the new comments are appropriately integrated.

Recommended Approach

1. Mutate Posts directly (Simple Fix)

One of the simplest methods is to mutate the post directly and then update the state with setPosts(posts):

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

This solution will certainly show the new comments immediately, although it involves mutating the posts array directly which is not the best practice in React as it can lead to unexpected behavior.

2. Using Map to Update State (Best Practice)

To avoid mutating the original state of your posts, it’s best to use the map function to create a new array while updating only the relevant post:

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

This approach follows React best practices by ensuring that the state is updated in an immutable way.

Conclusion

By following the guidelines mentioned above, you should be able to successfully display new comments immediately after submission. Utilizing either the direct mutation (for quick fixes) or the map method (for cleaner code) will help improve your user experience substantially.

Final Thoughts

In web development, understanding how to manage state correctly is vital. With tools like React, you now have the power to build interactive and user-friendly applications. Emphasizing best practices will not only help in maintaining cleaner code but also reduce potential future issues.

If you have any further questions or need clarification on certain aspects, feel free to reach out or leave a comment below!