Substack: scroll-to-top button
Adds a floating button that appears after scrolling and jumps to the top of the post in one click.
Code to copy
// Floating scroll-to-top button on long posts
(function () {
if (document.getElementById('jz-sub-top')) { return; }
var btn = document.createElement('button');
btn.id = 'jz-sub-top';
btn.type = 'button';
btn.textContent = '↑';
btn.title = 'Scroll to top';
btn.style.cssText = 'position:fixed;right:18px;bottom:60px;width:40px;height:40px;border-radius:50%;border:none;background:#ff6719;color:#fff;font:700 18px/1 system-ui,sans-serif;cursor:pointer;box-shadow:0 2px 8px rgba(0,0,0,.25);opacity:0;transition:opacity .2s;z-index:99998;';
btn.addEventListener('click', function () { window.scrollTo({ top: 0, behavior: 'smooth' }); });
document.body.appendChild(btn);
function toggle() {
btn.style.opacity = window.scrollY > 600 ? '1' : '0';
btn.style.pointerEvents = window.scrollY > 600 ? 'auto' : 'none';
}
toggle();
window.addEventListener('scroll', toggle, { passive: true });
})();How to use this example
- Copy the code with the button above.
- Install JustZix (2 minutes) and open the extension on the target page.
- Add a new rule matching that page.
- Paste the code into the rule's JavaScript panel and save — it runs on every page visit.
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