rerender-lazy-state

SKILL.md

Pass a function to useState for expensive initial values. Without the function form, the initializer runs on every render even though the value is only used once.

Use lazy initialization when computing initial values from localStorage/sessionStorage, building data structures (indexes, maps), reading from the DOM, or performing heavy transformations.

For simple primitives (useState(0)), direct references (useState(props.value)), or cheap literals (useState({})), the function form is unnecessary.

Use lazy state initialization with useState function form. Apply when computing expensive initial values like building search indexes, parsing JSON, or complex calculations. Source: theorcdev/8bitcn-ui.

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