Answer
useState(() => ...) runs the initializer only once during the first render, avoiding repeated expensive computations on every render.
Quick Answer
useState(expensiveComputation()) runs expensiveComputation on every render — but only the first render uses the result. Lazy initialization passes a function: useState(() => expensiveComputation()) — React calls it only on the first render. Essential when initial state requires parsing large data or running heavy computation.
S
SugharaIQ Editorial Team
Verified Answer
This answer has been peer-reviewed by industry experts holding senior engineering roles to ensure technical accuracy and relevance for modern interview standards.
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Source: SugharaIQ