useConst

Category

Utilities

Export Size

130 B

Last Changed

5 days ago

Return a value that is computed once, on the first render, and then returned unchanged — same value, same reference — on every later render.

Demo

Usage

import { useConst } from '@reause/shared'

const config = useConst(() => buildExpensiveConfig())

The value is not reactive. Changing the argument after the first render has no effect, and mutating the returned value does not re-render the component — useConst is a constant for the lifetime of the component instance. That is exactly what makes it safe to use as a stable dependency:

const options = useConst({ immediate: true })

useEffect(() => connect(options), [options]) // runs once — `options` never changes

The value lives in a ref, so the hook is also safe under concurrent rendering and server rendering: the first (or hydrating) render computes it once.

Type Declarations

export function useConst<T>(initialValue: T | (() => T)): T

Source

Source · Demo

Contributors

Changelog

v0.1.6 on

c39e8 - feat(shared): add useConst (#913)