Super Hover

A super tiny library that hit-tests hover every frame. Unlike native :hover, it keeps tracking whatever sits under your pointer while you scroll or when things move on screen.

Why use this?

Well, you probably shouldn't. While scrolling, browsers mostly skip updating :hover to prioritize other important rendering work, which in most cases is the desired behavior. But Super Hover recomputes a hover-like hit every frame, which opens up the possibility of some fun creative effects and interactions.

Installation

1pnpm add super-hover

Usage

Wrap the area you care about, then mark the things that should act hoverable.

The active element gets data-super-hover-active, which is usually enough if you only want styling.

1import { createSuperHover } from "super-hover";
2
3const root = document.querySelector<HTMLElement>("#list")!;
4
5const superHover = createSuperHover({ root });
6
7// later
8superHover.destroy();

1<ul id="list" class="space-y-1">
2  <li
3    data-super-hover
4    class="rounded-md px-3 py-2 data-[super-hover-active]:bg-neutral-100"
5  >
6    Inbox
7  </li>
8  <li
9    data-super-hover
10    class="rounded-md px-3 py-2 data-[super-hover-active]:bg-neutral-100"
11  >
12    Projects
13  </li>
14  <li
15    data-super-hover
16    class="rounded-md px-3 py-2 data-[super-hover-active]:bg-neutral-100"
17  >
18    Settings
19  </li>
20</ul>

Events

If styling is not enough, you can run code when the active element changes. Super Hover dispatches three custom events:

• superhoverenter when an element becomes active
• superhoverleave when an element stops being active
• superhovermove while an element is active

In TypeScript, listen for those events on the root. They bubble from the active element.

1import {
2  createSuperHover,
3  type SuperHoverEventDetail,
4} from "super-hover";
5
6const root = document.querySelector<HTMLElement>("#list")!;
7
8root.addEventListener("superhoverenter", (event) => {
9  const e = event as CustomEvent<SuperHoverEventDetail>;
10  console.log("entered", e.detail.current);
11});
12
13root.addEventListener("superhoverleave", (event) => {
14  const e = event as CustomEvent<SuperHoverEventDetail>;
15  console.log("left", e.detail.previous);
16});
17
18const superHover = createSuperHover({ root });

superhovermove is on by default in the core library. If you do not need move events, pass moveEventType: false.

Event detail

The events are CustomEvents, so the useful data lives on event.detail.

For superhoverenter and superhoverleave, detail has:

• x and y: the last pointer position, in viewport coordinates
• previous: the element that was active before this change, or null
• current: the element that is active after this change, or null

For superhovermove, detail has:

• x and y: the last pointer position, in viewport coordinates
• current: the currently active element

previous and current are DOM elements. If you need a value from your item, read it from the element with dataset, id, or whatever you rendered there.

1import type { SuperHoverEventDetail } from "super-hover";
2
3root.addEventListener("superhoverenter", (event) => {
4  const e = event as CustomEvent<SuperHoverEventDetail>;
5  const { x, y, previous, current } = e.detail;
6
7  console.log(x, y);
8  console.log(previous?.id);
9  console.log(current?.id);
10});

How it works

The library is very simple and short, so please read the source code (or ask your agent) for the full details.

In short, Super Hover keeps track of the last pointer and when the pointer moves, the page scrolls, or the viewport changes, it schedules a hit-test with requestAnimationFrame. Multiple updates in the same frame are coalesced, so they only produce one hit-test.

On that frame, Super Hover calls elementFromPoint(x, y), finds the closest element matching [data-super-hover], and updates the active element.

If the active element changes, Super Hover removes data-super-hover-active from the old element, adds it to the new one, and dispatches the custom events.

What about content-visibility?

Optimizing heavy content with content-visibility: auto can also make native hover feel more responsive. It lets the browser skip rendering for content until it is needed, which can leave enough room for :hover to update more often while scrolling.

That said, what the browser schedules, and how it prioritizes those updates is a bit of a black box to me, and the result does not seem fully deterministic. Super Hover, on the other hand, recomputes the active element from the last pointer position every frame. Of course, if the page is overloaded enough to drop frames, Super Hover can drop frames too.

If you have better insight into how browsers prioritize this, please reach out. I would genuinely love to hear it.

Accessibility

Super Hover can make the interface change quickly during scroll or animated layout changes, which can be jarring for people who are sensitive to motion.

If you use it in production, please respect reduced-motion preferences. Either disable it when it makes sense,or provide an equivalent opt-out.

1import { createSuperHover } from "super-hover";
2
3const root = document.querySelector<HTMLElement>("#list")!;
4const media = window.matchMedia("(prefers-reduced-motion: reduce)");
5
6const superHover = createSuperHover({
7  root,
8  enabled: !media.matches,
9});
10
11media.addEventListener("change", (event) => {
12  if (event.matches) {
13    superHover.pause();
14  } else {
15    superHover.resume();
16  }
17});

API

SuperHoverOptions

createSuperHover registers listeners for pointer moves, scroll, and resize, then hit-tests on scheduled animation frames. Pass these fields as options. It returns a controller with pause(), resume(), refresh(), and destroy().

On each scheduled hit-test, the library calls elementFromPoint, walks ancestors with closest(selector) to pick the nearest matched element, and—when root is set—verifies that it lies inside root. selector decides which nodes may activate; root only limits where hits count—it does not automatically target every descendant.

SuperHoverController

Returned by createSuperHover.

SuperHoverEventDetail

Used by superhoverenter and superhoverleave.

SuperHoverMoveEventDetail

Used by superhovermove.