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