Function usePrevious

packages/solid-router/src/utils.ts:3–21

(fn: () => boolean)

import * as Solid from 'solid-js'

export const usePrevious = (fn: () => boolean) => {
  return Solid.createMemo(
    (
      prev: { current: boolean | null; previous: boolean | null } = {
        current: null,
        previous: null,
      },
    ) => {
      const current = fn()

      if (prev.current !== current) {
        prev.previous = prev.current
        prev.current = current
      }

      return prev
    },
  )
}

/**
 * React hook to wrap `IntersectionObserver`.