Jelly UI: Soft-body physics for native HTML form controls

14 hours ago (jelly-ui.com)

Saw the window was a bit laggy so thought I'd delve deeper to figure out what was going on.

This lib runs a a RAF animation loop every 8ms across every component on the page that causes the entire document to repaint.

The comment above appears of the AI generated sort: // One shared animation frame: step every live component, park when idle. // The delta is capped so a background-tab pause never becomes one giant step.

The "JellyEngine" instead of just calculating the jelly animation on pointer events is recalculating for every active component on the page every frame.

This is the kind of thing usually a human notices and says 'dont do that, that is kind of crazy'.

  • Running a performance profile in Chrome doesn't back this up for me, and looking at the loop it looks like it maintains an active `Set<JellyComponent>()` of which components to update, and clears them out when they stop moving.

    Agreed the comments look a bit slop-ish but I don't see anything obviously wrong with its approach, and the core loop is running in microseconds for me when nothing is happening.

    • Here's the perf profile, just to clarify.

      Cursor idle, viewport on the button examples. 3ms repaint every 8-11ms. Animation frame points to the code i mentioned.

      https://postimg.cc/sQpZxxzv

      The problem isn't doing work on a website, its if you have an idle task that is taking up a significant portion of the frame budget then its easy to have frame drops when you do significant work like clicking, scrolling, browsing.

      Idle work showing up in flamecharts is usually the thing to be cautious of.

      3 replies →

  • > This is the kind of thing usually a human notices and says 'dont do that, that is kind of crazy'.

    It's not crazy. That is literally what 99.99% of video games do. They repaint everything constantly, only limited by either your vsync rate or hardware.

Cute (and I mean that sincerely, not sarcastically), and I appreciate that it appears to gracefully degrade for `@media (prefers-reduced-motion: reduce)`, but for the demo site, it would probably be a good idea to allow the user to override that without having to change their system settings, or at least alert them that they won't see the animations.

  • I'm glad I read your comment, I missed that it intentionally gracefully degraded and assumed it was broken, as I'd forgotten I'd set that.

  • PSA: Apple menu > System Settings > Accessibility > Motion

    These cool demos come up now and again and it always takes me a minute to remember I have reduced motion. But for that minute I was disappointedly clicking around thinking "Whats the big deal?"

  • Point taken and now you both get notifications as well as a pretty bunny icon to click on, to over rule the system settings.

I love this, but it does not seem to conform to standard UX best practices.

If I click and hold then move the mouse away to release, I assume an element should not register that as a click. As-is, this is inconsistent: the button registers a click, the checkbox does not.

  • I always had this issue when working with Flash developers. A common mantra was "don't reimplement scrollbars unless you can implement all the features a scrollbar comes with." They always had to do more than five iterations and spent days on that scrollbar.

  • Good catch. I've updated the button logic. The click will no longer trigger if the cursor is outside the button boundary.

If I were younger I would love this. nowadays I spend most of the time tweaking websites to remove this stuff using local stylesheets...or using dark + read mode... how times have changed.

  • I like the fact that it gives animated feedback to emphasize what is happening/being altered. Native components don't always do that very well. Animations are not just artsy fluff, they have real UX value (if done right, of course).

    • I think the trick to using libraries like this is to not go all in on them. Applying these effects to every element would be garish.

      But for a single like button, an effect slider, or magic search bar? It would be be a lovely touch.

    • Honestly same, I was less interested in the styling and just interested in the immediacy of response which is ironically missing in a lot of modern ui

  • I flip back and forth every year or so between wanting more fun in my software, and wanting it to get the hell out of my way.

    • "There's a time and place for everything, but not now!"

      I think now that llms make it super easy to add anything that its important not to add everything.

This comment is for like three people on HN, but anybody remember when Paul Neave had a website/blog/showcase (c.2007-2010ish?) where the borders of the page had similar jelly effect? That was achieved with Flash back in the day.

Neave was a personal hero of mine back then... hope you're well if you're reading this!

It's cute. But the reaction time on some of the controls is so awful. If I click and drag the slider control back and forth, it lags behind the mouse cursor substantially. It should feel like it's stuck to the mouse cursor like glue.

By contrast, most of the other controls do seem to stick to the cursor, such as jelly-resizable.

Also, the "Placeholder" control seems to fail to actually make the placeholder disappear when clicked in.

I'm having trouble identifying any physics at all in this UI design system.

  • The library does respect the client-side reduce motion setting (by disabling all animated effects).

    • EDIT: OH MY GOD THAT IS A HUGE CHANGE!! On MacOS: Settings -> Accessibility -> Display -> Reduce Motion. I had no idea that was on. I like motion, I wouldn't have set this myself!

      ------------------

      Original:

      How does that make anything about this "physics-based"? I'm not being snarky, I'm genuinely trying to figure out what part of this is completely going over my head. I don't see any "soft-body physics" interactions, but maybe I don't understand what to look for.

      I don't see any deformation or elastic collision physics, and those are usually the most obvious things that I associate with "soft bodies" in engineering/physics.

      3 replies →

    • Oh, thanks for the hint. I actually don't like this - similarly to dark mode setting detection. But I guess thats more a criticism on the OS preferences not being granular enough.

      1 reply →

I think it would be nice if the effect happened on hover as well, maybe to a lesser degree. Also, some of the controls don't appear to have any jelly in them, like the progress bar, toast, and so on. Finally, the performance on that showcase page isn't the best, and it feels like you're hijacking the scrolling somehow. But overall, it's cute. Would fit nicely as a game's UI.

I dont get why people are so mad at this? Looks fun, will I ever use it? Probably not, but it looks fun

  • A single function button should not behave differently based on where on the button you click it.

    EDIT: It's also WILDLY inconsistent. Click and drag on a button and the shape doesn't change. Click and drag on an on/off and the deformation follows the mouse. Merely click an on/off and the deformation does not follow the the little circle thingy, or bear any relation to the action of the button.

    Some of the things are inoffensive, spinner dots, progress bars, accordion menus. But basically anything that deforms on click related to where you click are nonsense.

    EDIT 2: The buttons in the demo area apparently do have distortion that follows the mouse, but on the left side they don't? For me this is just a lot of bafflingly inconsistent gloss that makes me wonder what's going on or why one thing behaves differently than others, and what that means for actual functionality. Rather than just interacting with the UI.

  • i think on HN you tend to get overly critical non-useful signals

    very important to filter out and choose who you engage with

Okay I know this is gonna sound rude but who in the world would want form controls that behave this way?

It could just be the particular type of my colour-blindness or my monitor settings, but the red and amber colours look so similar that I couldn't tell that I had even clicked the button.

- anyone mind explaining to a beginner what kind of algorithm is used to achieve this effect

- i can see it changes size on clicking and dragging

- so what is the author actually doing?

that's a real frustrating form of scrolljacking, a forced timed animation & lockout for concurrent scroll events until the timer is relinquished and input ceases; impressive.

Nice idea but I feel like it would work better with a non-flat or mildly-3D theme.

I don’t like the Chip element it’s supposed to stay in place and toggle instead it goes out of bounds when clicked.

This could be modified to be very useful for folks with less-than-ideal hand ability. I don't have much fine motor control in my hands. Hitting one of the modern tiny targets usually involves clicking a few times around the target until I finally manage to randomly twitch the mouse into the right place. Something like this, where the target changes shape to improve targeting ability or increase the size of the click zone, would be wonderful.

This is cool, but overdone to the point of distracting. Subtle effects can enhance usability but it should be barely noticeable.

Ew ew ew visceral uncanny valley reaction to the on/off control. I never made it to scrolling.

  • I'm torn between ugh and ick.

    It's poorly implemented and looks crude and unpolished.

    There might be an idea there, for limited applications, but this isn't it.

Is there an easy way to “reverse” the effects here? For example, on the “Jelly Button” I don’t want the part I press on to get bigger. I want it to get smaller and “inflate” the other parts of the controls that aren’t under my finger.

I love it - stupidly creative - first time i see this yet it feels I always knew how it was meant to behave

I'm so glad it allows for preferences to reduce motion. I don't like these kinds of UIs at all... unless maybe I'm inside a video game and even then it bothers me after the initial novelty.

on chrome on a macbook pro page scrolling is noticeably degraded and animations are low fps. It's a very subtle effect which is nice i guess, but the feeling of jankiness overrides it.

I'm not sure I get why the slider lagging behind where the pointer that's dragging it is a good thing.

It's fun, but a menu would be so much better instead of the weird scroll-jacking. It takes a minute to get to the bottom of it.

Your scroll is messed up on my Macbook M3 Pro / Opera, it's like a broken "velocity scroll" that is too loose and scrolls past several items leading to a clunky experience

This would be awesome if someone could add 3D rendering to make it actually look like I’m pressing a little jelly ball. It would make it so fun to press buttons that CA and EU would have to make jelly buttons illegal.

Some review of Jelly UI itself.

—⁂—

It requires JS to work, which could have been avoided at some arguable ergonomic cost. Personally I’d disqualify it from being considered “native HTML form controls”—it’d need to be just an enhancement to qualify in my mind.

—⁂—

Your sets of chips like mode auto/dark/light should be marked up and behave as radio buttons: when one is checked, it should be the only one in the tab order, and arrow keys and such cycle through them. <jelly-segmented> gets this right.

—⁂—

The demos show a “click” toast on buttons even if you move out of the button before releasing, which should cancel it. Either the event handler is linked to something other than activation (which should be fixed), or activation behaviour is wrong (which should be fixed).

—⁂—

> <jelly-checkbox indeterminate>

Oh how I wish <input type=checkbox> had an indeterminate attribute and a way of telling it to cycle through indeterminate when clicking. As it is, it’s purely a property, not attainable in serialised HTML.

—⁂—

> <jelly-otp>

I hate it. Do not under any circumstances use a sequence of single-character inputs for OTPs. It behaves really nastily. Sure, you made the simple paste case work, but all kinds of other normal interactions are busted. You must use one input. If you want to style it in a way that shows the intended length and puts characters in those boxes, you can still do it. Use `font-variant: tabular-nums` or `font-family: monospace`, then rely on the ch unit and probably add some letter-spacing (one of the very few legitimate cases for letter-spacing), and draw behind. Or, if you want more control… contenteditable is available.

—⁂—

> <jelly-range>

I thought we were talking “native HTML form controls”? There ain’t no such thing in HTML. (It becomes apparent the further I go that it’s not intended to be limited to what HTML has.)

—⁂—

> <jelly-switch>

There’s a gap in the hit target between the switch and the label. This needs to never happen. It didn’t seem to with checkboxes or radio buttons.

—⁂—

> <jelly-textarea>

Hold down a letter until it gives up expanding, and I found text and scrollbar drawn on top of the jelly border.

—⁂—

> <jelly-alert dismissable>

The × hit target is much too small.

—⁂—

> <jelly-pagination>

Not pleasant to use. Bad hit targets (too small, gaps between), poor choice of pages to offer (‹ 1 … prev self nextlast ›: you want 2 instead of … if prev is 3, and you want more than one prev/next), and if it’s ever going to be interactive, the layout changes far too much.

—⁂—

> <jelly-tabs>

Ugh. Ugh. Unpleasant appearance, presenting tab bar and panel as unrelated widgets. Bad cross-fade (opacity drops below 1).

—⁂—

> <jelly-dialog>, <jelly-drawer>

Opening it in dark mode was very jarring: no transition, and the backdrop lightens (should darken; that may require changes to the dialog background colour).

—⁂—

> <jelly-menu>

You reused a <select> dropdown, and it shows. Interactions are all wrong. It also says “typeahead keyboard support” but I see no such thing.

This is surprisingly delightful to play around with. We have to put some more fun into UIs, not the same type of AI-slop everywhere.

Please never use scroll-snap as is done on this demo page (unrelated to the soft-body physics). It leads to an awful experience for a large fraction of users. It improves things in one or two scenarios, but at the cost of far more common great frustration.

Scroll-snap is a really risky feature, very niche in its reasonable applications. This is definitely not a suitable place to use it.

  • > It leads to an awful experience for a large fraction of users.

    can you give an example of why/how? I thought it was well done and enjoyable. Regular fast scroll was still as expected, and then the slower interactions felt like slide changes.

    • Nobody expects the scroll behavior to be different on a webpage, so it's always a surprise when a page does something like this. Then, you have to learn to adapt to how it expects you to scroll so that you don't screw up its animations or overshoot.

      It's the kind of UI that works if you scroll a specific way. A lot of people probably do. But if you don't, it's all very tedious. I consider that to be poor design.

    • It ignores my scroll wheel most of the time if I try to scroll multiple times in a row.

      The scroll is delayed significantly from when I scroll to when it actually scrolls.

      The amount scrolled is inconsistent, sometimes it scrolls a very slowly a tiny amount because the page doesn't fit on the screen by an unknown tiny fraction, but if I scroll again because it is scrolling both slowly and with delay it now scrolls an entire page.

      If I want to scroll past one of the demos I have to wait

      If I drag the scroll bar on the side slightly it often snaps backwards.

      It feels like I'm interacting with a phone/tablet screen on a computer, there's a reason why windows 8 failed.

    • It just violates my expectations, and thus feels frustrating. And there's almost no benefit.

      It would be like if my shoes suddenly made me take steps at perfect widths, and no matter how/where I tried to step on my own, they forcibly move my foot to the spot they think is best. Like, okay, I see the good intentions here. But I have no trouble walking on my own. I don't need help. So I'm not sure what problem this solves. And this would obviously feel jarring and awkward, and would take a lot of getting used to until it didn't.

      Except at least my shoes go with me, so presumably if I had a pair of auto-stepping shoes I would get used to them over time. But this website is a one-off, I'm going to visit once and never again, so it's just going to be weird and jarring, and then I'll leave.

    • For me, I scrolled, clicked, but the page hijacked my screen, moved its position by force, and I was not certain which pane I was on immediately. It broke my sense of continuity.

      I am only being literal when I say this, but as someone who is actively keeping an eye out for this sort of thing (CSS frameworks, UI kits), I lost interest pretty immediately when I saw that and closed the tab immediately. Assuming the people who made this page also made the UI kit, it tells me their web design values run contrary to mine.

      I don't even fall into one of the exceptional cases, and this was a very bad using-a-website experience for me.

    • Some of the "slides" have more content than fits vertically in the viewport, and trying to scroll to the bottom to see it without getting bounced to the next slide or back to the top is very touchy and tedious.

    • Different browsers handle scrolling differently, and people use a myriad of different "pointer" input devices, there's too many permutations to handle correctly. It's for similar reasons why building native inputs from scratch are fraught with peril (see this item from a few days ago)

      https://news.ycombinator.com/item?id=48930136

    • I’m on my phone and scrolling this page just leads to it constantly jumping up and down and makes it difficult to read as nothing stays in one place if I scroll a little bit.

    • It is bad because you are deciding something for ME, the user. That's bad UX because I want to decide my own experience and scroll jacking is the worst thing you can do for UX. Stop doing this.

      1 reply →

    • On a desktop or laptop computer, most trackpads have an immediate response curve. I am using one now, an Apple Wireless Trackpad. A very large amount of engineering effort over decades of time and millions of lifetime hours went into making it behave that way over a common wireless medium. I scroll a little bit, it scrolls a little bit, immediately, I scroll a lot, it scrolls a lot, immediately, and if I flick my finger from the bottom to the top and let go, it behaves as if I swiped a page of paper on my desk in the same fashion, with inertia taking over, proportional to how fast I flicked.

      There is therefore an intrinsic physical link between the actions of my fingers, and the motion on the web page. My finger moves, and an immediate, proportional response is observed. This is an utterly base level of how most humans interact with the world. It is why using a mouse or trackpad came quite easy to many people (and why some can flick a mouse in a shooter, turn a precise 274.9 degrees, move up 14.2 degrees, and click on the head of an enemy player in fractions of a second with pinpoint accuracy). It is also why even a toddler can use a touchscreen; direct manipulation is inherently understandable to even a baby.

      When I am turning in a screw by hand with a screwdriver, the feeling of the screws threads through the handle into my fingers, the immediate force feedback, the observable, feelable progress of the screw in or out of its screwhole, forms this same interface. Where human and tool meet, latency and unexpected behavior, especially if divorced from the input force, are undesirable qualities of a tool.

      Scroll jacking is to a trackpad or a fine scroll wheel as turning a screwdriver handle by twisting a bungee cord is to using a screwdriver. It unhooks the immediate, direct feedback from the motion of my hand; its jarring, unpleasant, frustrating. On this page, I immediately put two fingers on the trackpad and moved them less than a centimeter, and didnt let go, and the entire screen cycled its view, as if I pressed a button "move to next item". Except I didn't (and why would I want that in the first place???), I just moved my fingers less than a centimeter. Nothing in the real world moves like that except for things less than a centimeter away from falling out of balance. And it feels the same. Precarious. A common human reaction to things moving out of proportion to our body is nausea!

      I think a better question is, can you give an example of "why/how" this solves any actual problem someone would have had scrolling this website had it not used scroll snapping? Would the top comment have been "Boy I wish this site had used scroll snapping, it would have been more well done and enjoyable that way"?

  • Agreed. I almost exclusively use the "middle click" autoscroll feature to scroll on websites. It is completely broken on this site because of the scroll-snap.

  • The scrolling behavior on this site worked great for me—it let each example stand on its own and meant I wasn't spending a lot of effort trying to figure out when a given example would end and the next example would begin.

    It doesn't look like there's anything custom going on here either, it's all just standard scroll-snap-* CSS properties. if you have an issue with the way your browser is handling the scroll-snap CSS properties, I recommend you take that up with your browser? After all, you should be using a user agent that works for you, not against you.

  • I liked it. I'm curious how it affected you negatively?

    • I moved my scroll wheel a single tick and the content of the browser window completely changed with no movement to indicate scrolling was happening.

      The change was so sudden and stark that I thought some sort of error had occurred and I was looking at a broken render of whatever I should be seeing.

      Might be slightly better if the background didn't change color as soon as you move off the first "slide". Then it might not feel like you left the site or got dumped to an error page.

Gotta say, I like most of the effects except for the wiggly "membrane" on inputs and buttons: I'd prefer to see the the whole thing jiggle when clicked or focused, rather than a small circle, and to turn off the effect entirely for typing. I suppose it's trivial enough to go into the source, but if there's a cheap and easy way to expose customization knobs like that, perhaps take it as a suggestion.