Скачать или смотреть useEffect react hooks code step by step

useEffect confusing you? Here's the breakdown that ACTUALLY makes sense

Here's useEffect step-by-step:

1. Basic useEffect: Runs after every render - use sparingly!
2. With dependencies: Only runs when specific variables change - this is what you want 90% of the time.
3. Empty dependency array: Runs only once when component mounts.
4. Cleanup function: CRITICAL for preventing memory leaks - always cleanup timers and subscriptions!

The 3 useEffect rules:

No dependencies = runs every render (usually bad)
Empty array = runs once (great for setup)
With variables = runs when those change (most common)

Pro tip: If you're not using cleanup functions, you're creating bugs. Period.

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