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> it's uncommon that I want more than 100 items

I believe the discussion is GUI items, not what you might consider data items. Look at this current Hacker News page. Each comment, depending on how fine-grained you're counting, looks to have about 5-6 or more GUI components. In your browser viewport you may see a dozen comments. GUI components add up quickly. These are also only the components in view. React, however, is rendering the entire page. Easily hundreds of React components.



But depending on how they're styled and what animations you're using, React can easily handle rendering out 1000 DOM nodes.

To be clear, I don't want to act like it's not a real concern, I've been in situations where the number of DOM elements I was rendering out with React ended up being a performance concern. It's a real thing. Heck, I've been in situations where React's insistence on computing the virtual DOM was a performance problem. One of the downsides of component-based architecture is that it's very easy to get into situations where you're completely pointlessly duplicating effort parsing data multiple times and passing it around between components and mapping it to new lists of data. It's a major weakness for systems like React that encourage you to loosely couple all of your components, even components that are inherently very related to each other.

But I think people are underestimating what that component/DOM limit is, even for browsers like IE 11.

If you have 100 items on screen, and it's causing the browser to slow down, you'd better be doing something at least somewhat complicated with those elements. You'd better be sticking some SVG charts in there or something. Otherwise I'm going to (perhaps uncharitably) accuse you of overcomplicating your DOM and inserting a bunch of nodes that don't need to exist.

If someone wants to try and implement HN in React, they shouldn't be using 5-6 separate React components for a single comment, that's... I don't know how to parse that kind of architecture. I don't want to be dismissive about it, and different people have different approaches to programming -- but I feel pretty strongly that kind of granularity is over-engineering.


Not OC but from my experience because you have some nested DIVs and spans and some other node elements for each data item when you first load your data you get a big hang/freeze because the browsers are still slow at creating this elements, this is a browser issue I think, because most of the time you want to have a big list of similar items there should not be such a giant work of creating and computing similar DOM elements but I assume because of how complex css engine is you get this giant freeze.


Eh... you really shouldn't get a big hang/freeze if you're just talking about inserting 1000 nodes into the DOM. It's not going to be fast enough that you can do it at 60fps, but that's not the point of the DOM -- 60fps insertion is not something we care about.

I mean, yes, some of this is dependent on CSS. If you're doing complex rendering, or doing something strange with your fonts. I'm not going to make absolute claims about performance in every case, and different people have different interactions and requirements they're dealing with. There's caveats.

However, if someone comes to me and says, "I put 1000 DOM nodes into the browser and my page froze", I might not immediately make strong claims about the application, but I am going to immediately start looking around the codebase suspiciously to see if they're doing something strange or abnormal.

The current HN page you're on right now has ~2500 DOM nodes. Does it freeze for you when you load the page?

People complain a lot about DOM insertion, but while DOM insertion does sometimes cause problems, I've found it's more often that the problems happened before the insertion. At the point where DOM insertion actually becomes a problem, I suspect we're usually no longer talking about lists of 1000 simple table elements, or just putting 100 search results on a single page.


I am not sure what I did wrong, maybe if I had set some min/max height/width on soem elements it would have improved the performance, or maybe if i changed some flex-box property so regular layout or maybe if I changed some css rule on some parent somewhere it would have worked better.

I am sure I can make a list with just text and not css I can insert 1000 text nodes in it, the issue is if you have something mroe complex like a grid with thumbnails and titles, and a small description under, and some css effect for hover, and a few buttons when you hover over those items etc. In a sane GUI this 1000 widgets are not created at all, only the visible ones are created and when you scroll the data under the Widget is swapped, this is great because you don't have to focus on performance or use pagination and then pretend pagination is better UX.

Just to clarify I agree that there should not be many DOM nodes in a page, the browser or framework widget should be smart and transparently recycle the existing DOM elements, I imagine there would be some new List and Grid widgets that are more advanced but that could be used by everyone with his favorite framework.


> In a sane GUI this 1000 widgets are not created at all, only the visible ones are created

As a side note, this gets a little bit at an issue I feel pretty passionate about, which is that HTML is not a language for laying out interfaces, it is a user-facing interface itself. HTML isn't for programmers, it's for users.

The sane GUI you're talking about is essentially virtual rows, they're just baked into many native toolkits. A native interface doesn't insert everything because it doesn't have to, its interface is purely visual. If there are accessibility controls, they happen through a separate interface. If there are keyboard controls, they're based on the widget, not based purely on the content.

This is not a universal opinion, you will find people who disagree with me on this. But I think the web is fundamentally different than that. The web at least attempts to force your text interface and visual interface to be the same.

I'm not sure if it was to you or someone else that I mentioned that many apps (even native ones) are really just interactive documents when you think about their data separate from their styling. In my mind, the innovation of the web is that it acknowledges that, and it forces your interface to be a pure XML-like tree. And then you can put some styling on top of that with CSS if you want to. There are a few exceptions to that, but for the most part, HTML doesn't really let you hide a ton of information.

So imagine if you were building an app in GTK, and GTK said, "okay, first give me a pure-text representation of your interface that I can pipe to a terminal. And then I will allow you to position boxes on the screen, but only from the text that you told me I can pipe to the terminal."

That's a very different paradigm than how most other application frameworks work, and I think that the DOM's insistence of not having a lot of opaque data-bindings where possible makes a lot more sense when viewed through that lens. That lens also helps explain why some devs (myself included) got very annoyed about Google messing with that paradigm because they had their own 'cute' idea for web components.

The downside of this paradigm is that the tools you're talking about like data-bound lists aren't natively built into the DOM. You end up needing to use 3rd-party Javascript libraries for them. But for the most part, due to Javascript's popularity, those libraries are easy to find. Although due to Javascript's popularity, sometimes they are of dubious quality. :)


I understand, HTML is a document but it has this disadvantages and IMO if we want to use HTML everywhere we need some default Widgets for List and Table, don't change anything about current HTML but similar on how we have a Video or Canvas element we might want something for this uses cases and not force each developer re-invent the wheel. If is not built=int he browser I would like some sane JS implementation (framework independent and without any dependencies on 100 left-pads),

This thing where each developer re=invents same thing over and over and each implementation is broken in some way it bothers me, like the search input in Youtube has a dropdown with some suggestion, that dropdown popup can get stuck open until you reload the page, so even Google engineers are not capable of implementing a 100% working simple Widget.




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