Techniques for handling concurrent requests and race conditions with error boundaries in React

06 Oct 2023

In a React application, handling concurrent requests and race conditions is essential to ensure the proper flow of data and prevent unexpected errors. One way to address this is by utilizing error boundaries, which help catch and handle errors within a specific component tree.

What are error boundaries?

Error boundaries are React components that can catch errors anywhere within their component tree, log the error, and display a fallback UI instead of the crashed component. By using error boundaries, you can prevent the entire application from crashing due to a single error.

Handling concurrent requests

To handle concurrent requests in React, one common approach is to use the Promise.all() method to wait for multiple promises to resolve before updating the component’s state with the fetched data. This ensures that all requests are completed before proceeding further.

Here’s an example of how you can handle concurrent requests using Promise.all():

import React, { useEffect, useState } from 'react';

const fetchData = async (url) => {
  const response = await fetch(url);
  const data = await response.json();
  return data;
};

const MyComponent = () => {
  const [data, setData] = useState([]);

  useEffect(() => {
    const urls = ['https://api.example.com/data1', 'https://api.example.com/data2'];

    const fetchDataAsync = async () => {
      try {
        const responses = await Promise.all(urls.map(fetchData));
        setData(responses);
      } catch (error) {
        console.error('Error fetching data:', error);
      }
    };

    fetchDataAsync();
  }, []);

  return (
    <div>
      {/* Render the fetched data */}
    </div>
  );
};

export default MyComponent;

Dealing with race conditions

Race conditions occur when multiple asynchronous operations are running simultaneously and the order of completion affects the desired outcome. To handle race conditions in React, you can use techniques like debouncing or cancellation to ensure that only the latest request’s results are used.

Here’s an example of how you can handle race conditions using debouncing:

import React, { useEffect, useState } from 'react';

const fetchData = async (url) => {
  const response = await fetch(url);
  const data = await response.json();
  return data;
};

const MyComponent = () => {
  const [searchTerm, setSearchTerm] = useState('');
  const [error, setError] = useState(null);
  const [data, setData] = useState([]);

  useEffect(() => {
    const delay = 500; // Debounce delay in milliseconds
    let timeoutId;

    const fetchDataDebounced = async () => {
      try {
        const response = await fetchData(`https://api.example.com/search/${searchTerm}`);
        setData(response);
        setError(null);
      } catch (error) {
        setError('Error fetching data');
      }
    };

    if (searchTerm) {
      timeoutId = setTimeout(fetchDataDebounced, delay);
    } else {
      setData([]);
    }

    return () => {
      clearTimeout(timeoutId);
    }
  }, [searchTerm]);

  return (
    <div>
      {/* Render the fetched data */}
      {error && <p>{error}</p>}
    </div>
  );
};

export default MyComponent;

In this example, the searchTerm state is debounced for 500 milliseconds. If a new search term is entered before the debounce period is over, the previous request is canceled using clearTimeout(), preventing outdated results from being displayed.

By implementing these techniques, you can handle concurrent requests and race conditions effectively in your React application, ensuring a smoother user experience.

#react #concurrency