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Discover effective solutions to eliminate the `one-second typing delay` in your React Native on-screen keyboard application.
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This video is based on the question https://stackoverflow.com/q/73152658/ asked by the user 'Edward Newborn' ( https://stackoverflow.com/u/9742026/ ) and on the answer https://stackoverflow.com/a/73155415/ provided by the user 'RodSar' ( https://stackoverflow.com/u/17898801/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Fix TextInput Lag in React Native Caused by an On-Screen Keyboard

Developing a mobile app comes with its unique challenges, particularly when it involves custom components like an on-screen keyboard. One common issue developers encounter when using a custom keyboard in React Native is text input lag, where there's a noticeable delay between key presses and text appearing on screen. If you're facing a frustrating delay, in this post, we’ll explore a practical solution to help you achieve smoother and more responsive text input.

Identifying the Problem

You may be facing a laggy input experience if:

Your custom keyboard is rerendering too often.

The TextInput component updates inefficiently.

State updates occur too frequently, leading to performance issues.

In this scenario, we have a user whose custom onscreen keyboard introduces a one-second delay when typing letters onto a screen. Let’s delve into a structured solution to overcome this issue.

Proposed Solution Overview

The main points of the solution include:

Using useCallback to optimize state updates.

Creating a memoized keyboard component to minimize unnecessary renders and improve performance.

Step 1: Optimize State Updates with useCallback

By using useCallback, you can memoize the function that adds letters to your text state. This improves performance by making sure that your function doesn’t get recreated on each render.

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

In the code above:

addLetter is a function that takes a letter as its argument and updates the name state by appending the new letter to the existing state.

This function only changes if setName changes, preventing unnecessary rerendering.

Step 2: Create a Memoized Component for Keyboard Keys

Building a separate component for your keyboard keys ensures that each key only re-renders when its props change. Use React's memo feature to create a KeyboardLetter component.

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

In this new component:

Each KeyboardLetter uses useCallback for its onPress event to ensure that it only recreates this function when necessary.

The button only updates when the addLetter function or letter prop changes.

Step 3: Using the Memoized Component

With your new KeyboardLetter component ready, you can integrate it into your keyboard layout easily. Use it like this:

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

By adopting this approach in your app, you should notice a reduction in lag when typing. Each keystroke should now reflect immediately in the TextInput without a significant delay.

Conclusion

Encountering input lag in your React Native application, especially with a custom keyboard, can be a hindrance to user experience. However, by optimizing your state updates using useCallback and creating memoized components for your keyboard keys, you can significantly enhance the responsiveness of your application.

Take these tips and see if implementing them helps resolve your keyboard lag issues. Happy coding!