React HooksLesson 48Free preview

React useEffect

This lesson is part of React · All levels

Summary

UseEffect runs side effects after a component is rendered to a DOM, such as retrieving data, subscribing to an event, or changing a page title. The dependency list determines whether the effect is run again, and the effect containing the cleaner should restore the cleanup function. Proper dependency prevents over-rendering and over-demanding.

Key points

UseEffect runs after rendering, not during rendering
Empty dependency [] means the effect is executed once when mounted
Dependencies contain values that run the effect when that value changes.
The cleanup function is run before the next effect and during unmount

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