React useEffect()

Creator
Creator
Seonglae Cho
Created
Created
2021 Mar 30 15:36
Editor
Edited
Edited
2025 Jul 15 9:16
Refs
Refs

Guarantees DOM updates before effect execution

Effects are an escape hatch from the React paradigm. If there is no external system involved you shouldn’t need an Effect. When something can be calculated from the existing props or state, don't put it in state. Instead, calculate it during rendering. You can cache or
React.memo
an expensive calculation by wrapping it in a
React useMemo()
hook.
It combines componentDidMount, componentDidUpdate, and componentWillUnmount. The double invocation in development environment is intentional by design (implying effects should be resilient to multiple calls).
 
 
 
 

Not need an effect

 

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