Скачать или смотреть Fixing the React keydown useEffect Issue on Initial Page Load

Discover why your React `keydown` event listeners might not work on page load and how to fix this with effective use of `useEffect` and `useCallback`.
---
This video is based on the question https://stackoverflow.com/q/75270528/ asked by the user 'UncleJerry23' ( https://stackoverflow.com/u/12400409/ ) and on the answer https://stackoverflow.com/a/75270614/ provided by the user 'Alexsander Gutierreez' ( https://stackoverflow.com/u/21090290/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: React keydown useeffect not working on page load

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting React's keydown Event Listener on Page Load

In the world of web development, creating seamless user interactions is crucial. If you're working with React and have encountered an issue where a keydown event listener doesn’t function as expected on initial page load, you're not alone. Many developers face similar problems, and the solution often lies in the correct application of hooks like useEffect and useCallback. In this post, we’ll explore the issue in detail and provide an actionable solution.

The Problem

You may be using a keydown event listener to trigger certain actions in your application, such as playing a video or processing user input. However, you might notice that this listener only activates after a refresh or after certain actions have occurred, which can be frustrating. For instance, you might find that when you first open the page and hit a specific key, nothing happens until a refresh occurs.

To illustrate, consider the following sequence:

Works When:

You open the page.

You make a code change (like adding a comment or making other edits).

React refreshes.

You hit the 'e' key.

The code works as intended.

Does NOT Work When:

You open the page.

You hit the 'e' key.

Nothing happens.

The problem might stem from how you've set up your useEffect hooks or your key press function. Let's dive into the solution.

Understanding the Solution

The key to resolving this issue lies in ensuring that your keydown event listener is set up correctly from the very beginning. Here’s how you can achieve that:

1. Use useCallback Effectively

In your current implementation, the keyPress function that defines the event listener uses useCallback. However, it’s vital to keep in mind that the dependencies of this function should include the ids state array. By doing this, you ensure that the function has access to the latest values of the ids when it executes.

Here’s the modified keyPress function:

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

2. Properly Set up the useEffect Hook

Next, ensure that your useEffect that adds the event listener includes the keyPress function correctly:

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

3. Maintain State Responsively

You also want to ensure that your state updates happen seamlessly without causing unnecessary re-renders or stale closures. Make sure your state logic is designed to function fluidly, maintaining references to state when needed.

Putting It All Together

Here’s how the complete Player function should look with necessary adjustments:

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

Conclusion

By employing the correct usage of useCallback and ensuring that your useEffect dependencies are well-managed, you can effectively resolve issues with keydown event listeners not functioning upon initial page load. Make these adjustments in your project, and you'll likely find that your React application's user interactions become much more responsive and intuitive.

Happy coding!