Optimizing Real-Time Suggestion Dropdowns in React: Using useCallback and useEffect
Tags: nextjs, react, javascript, webdev
Published: 2023-03-22 12:26:04

In this article, we will delve into the process of creating a real-time suggestion dropdown component using React's useCallback hook.

Let's first understand how useCallback works. In React, the component's functions, including any passed as props to child components, are re-created every time the component re-renders. This can result in unnecessary re-renders of child components, which can impact your app's performance. The useCallback hook helps optimize app performance by memoizing functions and only re-creating them if the dependencies passed to it have changed.

Now let's take a look at this simple example code:

```
import React, { useState, useCallback } from 'react';

const TAGS = ['Apple', 'Banana', 'Citrus', 'Dragon fruitf'];

const SuggestionDropdown = () => {
  const [tagInput, setTagInput] = useState('');
  const [suggestions, setSuggestions] = useState([]);

  const handleTagInputChange = useCallback((e) => {
    const inputValue = e.target.value;
    setTagInput(inputValue);
    const sugList = TAGS.filter(tag => tag.startsWith(inputValue));
    setSuggestions(sugList);
  }, [tagInput]);

  return (
    <div>
      <input type="text" value={tagInput} onChange={e=>handleTagInputChange(e)} />
      <ul>
        {suggestions.map((tag, index) => (
          <li key={index}>{tag}</li>
        ))}
      </ul>
    </div>
  );
};

export default SuggestionDropdown;

```

In this code, we first define an array of tags that we'll use as our data source for suggestions. We then declare two state variables using the useState hook: tagInput, which represents the user's input in the text field, and suggestions, which holds an array of suggestions based on the user's input.

One key point to consider when making a real-time suggestion dropdown is the potential delay that can happen as the user types. Without proper optimization, the dropdown can be slow or even freeze, leading to a bad user experience.

This is where the useCallback hook comes in handy. As mentioned earlier, it memoizes the function and only re-creates it if the dependencies passed to it have changed. By doing so, unnecessary re-renders can be avoided, resulting in a smoother and faster user experience.

Besides, without the useCallback hook, the tag suggestions might not be updated immediately. This is mainly due to  `setTagInput`  is an asynchronous function, meaning that the state update may not happen immediately. Therefore, when you try to access the updated  `tagInput`  state variable immediately after calling  `setTagInput(InputValue)`, it may still have the previous value.

In conclusion, using useCallback is essential when creating real-time suggestion dropdown components to ensure optimal performance and a seamless user experience.

References:

-   [Building a tag input field component for React - LogRocket Blog](https://blog.logrocket.com/building-a-tag-input-field-component-for-react/)
    
-   Example in typescript =>  [joc-rgb/tutorMe (](https://github.com/joc-rgb/tutorMe)[github.com](http://github.com/)[)](https://github.com/joc-rgb/tutorMe)
    
-   [Master of Everything (openai.com)](https://chat.openai.com/chat)