Hacker News: back-to-top button
Adds a floating button that jumps back to the top of the page with one click after scrolling a long thread.
Code to copy
// Add a floating back-to-top button for long threads
(function () {
if (document.getElementById('jz-hn-top')) { return; }
const btn = document.createElement('button');
btn.id = 'jz-hn-top';
btn.textContent = '↑ Top';
btn.style.cssText = 'position:fixed;bottom:20px;right:20px;z-index:9999;' +
'padding:8px 14px;background:#ff6600;color:#fff;border:none;' +
'border-radius:6px;font-weight:bold;cursor:pointer;display:none;' +
'box-shadow:0 2px 6px rgba(0,0,0,0.3);';
btn.addEventListener('click', function () {
window.scrollTo({ top: 0, behavior: 'smooth' });
});
document.body.appendChild(btn);
window.addEventListener('scroll', function () {
btn.style.display = window.scrollY > 600 ? 'block' : 'none';
});
})();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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