zhibo/hooks/usePageScrollOpacity/usePageScrollOpacity.js

export const usePageScrollOpacity = (scrollTop) => {
	let opacityNum = 0
	if (scrollTop >= 0) {
		if (scrollTop <= 20) opacityNum = 0
		else if (20 < scrollTop && scrollTop <= 100) opacityNum = scrollTop / 100
		else if (scrollTop > 100) opacityNum = 1
	}
	return opacityNum
}