From the course: Master React 19 and Next.js 16 with Hands-On Projects and Real-World Applications

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React effects review: Common mistakes and best practices

React effects review: Common mistakes and best practices

From the course: Master React 19 and Next.js 16 with Hands-On Projects and Real-World Applications

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React effects review: Common mistakes and best practices

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Welcome back! In this session, we're reviewing everything we've learned in the React effects chapter. This is where React starts responding to changes over time, whether that's fetching data from an API, listening to events, or cleaning up resources when components unmount. Let's start with the most common use of useEffect – fetching data when the component mounts. Notice that we pass an empty dependency array – empty brackets – so this effect runs only once. Remember, without the empty array, the effect would run on every render, which could cause infinite loops. Next, we add dependencies to useEffect. Here, the effect runs whenever the city state changes. A common mistake is forgetting to include dependencies, which could lead to stale data or missing updates. Always list all state or props that your effect depends on. Any variable or value used inside your useEffect should be listed in the dependency array. This ensures React runs your effect whenever those values change, keeping…

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