Скачать или смотреть Why throttle from Lodash Doesn’t Work in Your useWindowSize Hook?

Discover why lodash's `throttle` function may not behave as expected in your React custom hooks, and learn how to fix it for optimal performance!
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This video is based on the question https://stackoverflow.com/q/70813317/ asked by the user 'utopia' ( https://stackoverflow.com/u/7361279/ ) and on the answer https://stackoverflow.com/a/70813494/ provided by the user 'İbrahim Akar' ( https://stackoverflow.com/u/10891403/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Throttle and Event Handling in React Hooks

When working on a React application, you might encounter performance issues due to excessive event handling, particularly during window resizing. A common solution is to use the throttle method from Lodash to limit how often your event function is called. However, you may notice that the throttle method does not behave as expected in your custom hooks, such as useWindowSize. Let's delve into the problem and understand how to resolve it.

The Problem: Throttle Not Working Correctly

In the context of the useWindowSize custom hook, the throttle function seems to be set up correctly, yet it’s failing to produce output as expected. You might have a code snippet similar to the following:

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

Observations

The console logs indicating the throttling are printed successfully.

However, the inner function within throttle (console.log('bam')) doesn't execute.

The core of the issue lies in how functions are recreated on every render in React, particularly when using inline functions.

The Solution: Use useCallback with Throttle

To tackle this problem, we need to ensure that our throttled function remains consistent across renders. This is achieved by utilizing the useCallback hook in React. Here’s how to modify your useWindowSize code effectively:

Step-by-Step Code Fix

Define your Resize Handler: Create a function that will be called when the window is resized.

Use useCallback: Wrap the throttled function using useCallback to ensure it remains the same on subsequent renders.

Invoke the Throttled Function Correctly: Call this throttled function inside your resize event handler.

Here’s the revised code:

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

Key Changes Explained

useCallback: By wrapping the throttled function in useCallback, the same instance of the function is maintained, preventing it from being recreated on every render.

Throttled Function Execution: Now, throttleFn(e); will execute the internal logic and print bam in the console as intended.

Conclusion: Mastering Throttle in React Hooks

Utilizing throttle from Lodash can greatly enhance your application's performance by limiting how often a certain operation (like resizing) is executed. However, to get it working seamlessly within your custom hooks, ensuring that functions remain consistent across renders is crucial. By implementing the useCallback hook, you can preserve the function reference, allowing your throttle to work as expected.

Now, you're not just aware of why throttle wasn't functioning properly, but you also have a clear path to implementing it correctly in your React applications. Happy coding!