Скачать или смотреть How to Run useEffect in ReactJS After Props Value Changes, But Only Once

Discover how to effectively utilize the `useEffect` hook in ReactJS to manage API calls without causing unnecessary loads on your app. Learn the best way to respond to prop changes while avoiding infinite loops.
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Efficiently Managing API Calls in ReactJS with useEffect

When developing applications with ReactJS, we often find ourselves needing to fetch data in response to prop changes. One such scenario might involve using the Google Places API for nearby searches and detail searches to gather hours of operation for various places. However, running API calls continuously can lead to performance issues and unintended behavior. In this guide, we will explore how to effectively use the useEffect hook to make calls only when a relevant prop changes, avoiding repeated executions and potential application crashes.

The Problem: Continuous API Calls

Imagine that your application uses the Google Places API to conduct a detailed search based on a set of place IDs received as props. You would typically use the useEffect hook to trigger a fetch call to your backend as soon as those place IDs change:

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The issue arises when this setup results in an infinite loop of API calls, especially as you could have many place IDs. Each time the API call completes, if it updates the placeIds, it leads to a continuous re-fetching of data. This not only affects your application's performance but could also lead to unnecessary costs if the number of requests skyrocket.

The Solution: A Controlled useEffect Hook

To avoid the above issue, we can implement a solution that allows the useEffect to respond to changes in props.placeIds, but only run once when it changes. Here’s how to do it:

Step 1: Use a Derived Prop

One of the simplest methods to control when the useEffect hook runs, is to use another prop that does not update with each API call. This derived prop can act as a trigger without causing the infinite loop.

For instance, you might consider keeping a simple boolean state that toggles only when the placeIds prop updates for the first time:

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Step 2: Fetch Data Only If Place IDs Are Present

You'll also want to ensure that your effect doesn't run if the placeIds are not yet available. This can be done by checking if props.placeIds exists before making your fetch call:

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Conclusion

Utilizing useEffect efficiently is crucial for any ReactJS application, especially when dealing with API calls based on changing prop values. By controlling how and when the useEffect hook runs, you can avoid costly repeated requests and ensure a smooth user experience.

Next time you're faced with similar challenges in your React application, consider applying these techniques to manage your API interactions sparingly and effectively. Happy coding!