24 lines
595 B
JavaScript
24 lines
595 B
JavaScript
|
export function backToTop(){
|
||
|
|
const btn = document.getElementById('btn--back-to-top');
|
||
|
|
if (!btn) return;
|
||
|
|
|
||
|
|
let lastY = window.scrollY;
|
||
|
|
let peakY = window.scrollY;
|
||
|
|
|
||
|
|
window.addEventListener('scroll', () => {
|
||
|
|
const currentY = window.scrollY;
|
||
|
|
|
||
|
|
if (currentY > lastY) {
|
||
|
|
peakY = currentY;
|
||
|
|
btn.classList.remove('is-visible');
|
||
|
|
} else {
|
||
|
|
if (currentY <= 800) {
|
||
|
|
btn.classList.remove('is-visible');
|
||
|
|
} else if (peakY - currentY >= 200 && peakY > 600) {
|
||
|
|
btn.classList.add('is-visible');
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
lastY = currentY;
|
||
|
|
}, { passive: true });
|
||
|
|
}
|