Скачать или смотреть Understanding Why the fetch Statement in Your React App Results in Two Calls

Discover the reasons behind your React app's `fetch` statement making two API calls and how to properly manage side effects using `useEffect`.
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Why Does My React App's fetch Statement Make Two API Calls?

If you're developing a React application and you've noticed that your fetch statement is resulting in two API calls, you're not alone in this issue! Many developers face similar situations where their usage of fetch leads to unexpected behavior. This can be frustrating, especially when trying to ensure efficient and optimized code. In this guide, we will explore this common problem and provide a clear solution to prevent multiple calls from occurring in your application.

Understanding the Problem

In your React app, the fetch function is called directly within the component's function. Here’s a simplified version of the issue:

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

Why it Happens

The key reason behind the double API calls is that the component containing this fetch statement re-renders every time its state changes. Each re-render triggers the fetch call again, causing multiple requests. In React, when the state or props change, the function body of the component runs again, leading to the issue you are experiencing.

Observing the Problem

You can verify this behavior using the Chrome Developer Tools by checking the Network tab. You may see two or more API requests triggered rapidly, which can clutter your application's performance metrics and lead to excessive data fetching.

The Solution: Using useEffect

To solve this issue and ensure that your API call occurs only once when the component mounts, you can leverage the useEffect hook. This hook allows you to perform side effects in function components and is the recommended way to handle fetch requests in React.

Implementing useEffect

Here's how you can update your code using useEffect:

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

Explanation of useEffect

Effect Hook: By wrapping your fetch call in useEffect, it tells React that you want to run your side effect (the fetch call) when the component mounts.

Dependency Array: The empty array [] as the second argument means the effect will run only once—just like the componentDidMount lifecycle method in class components. This prevents the multiple calls you were experiencing.

Conclusion

By adopting the useEffect hook for your fetch statements, you can ensure that your React application operates efficiently and avoids unnecessary API calls. This optimization not only enhances performance but also leads to a cleaner, more manageable codebase.

If you're encountering issues with multiple calls in your own applications, remember this simple fix and see how it improves your app's functionality!

Feel free to share your experiences or ask questions in the comments below. Happy coding!