31 lines
751 B
JavaScript
31 lines
751 B
JavaScript
(function() {
|
|
'use strict';
|
|
|
|
function trackScroll() {
|
|
var scrolled = window.pageYOffset;
|
|
var coords = document.documentElement.clientHeight;
|
|
console.log(coords,scrolled);
|
|
|
|
if (scrolled > coords) {
|
|
goTopBtn.classList.add('back_to_top-show');
|
|
}
|
|
if (scrolled < coords) {
|
|
goTopBtn.classList.remove('back_to_top-show');
|
|
}
|
|
}
|
|
|
|
function backToTop() {
|
|
if (window.pageYOffset > 0) {
|
|
window.scrollBy(0, -30);
|
|
setTimeout(backToTop, 0);
|
|
}
|
|
}
|
|
|
|
var goTopBtn = document.createElement("div");
|
|
goTopBtn.id = 'back_to_top';
|
|
goTopBtn.innerHTML = 'UP';
|
|
document.body.appendChild(goTopBtn);
|
|
|
|
window.addEventListener('scroll', trackScroll);
|
|
goTopBtn.addEventListener('click', backToTop);
|
|
})(); |