4 ms·

"The DOM is slow": with all the advancement of the JS engines we'll hit a wall if the DOM does not start improving by an order of magnitude. Is this a fundamen

"The DOM is slow": with all the advancement of the JS engines we'll hit a wall if the DOM does not start improving by an order of magnitude. Is this a fundamental problem or is this a case of JS being so bad that now that it's faster it is exposing a need to focus on the DOM?

kevincennis 12y ago
It depends entirely on what your app does – but yes, I'd paint this as a fundamental problem for any app that needs to render a large amount of content (and keep it updated).
danabramov 12y ago
>with all the advancement of the JS engines we'll hit a wall if the DOM does not start improving by an order of magnitude We already hit that wall a long time ago. DOM is the bottleneck in any non-trivial app (unless your app mines bitcoins or something).
- shawndumas 12y ago
  Agreed! Further, things like DOM diffing help but are an optimisation and can only take us so far. The answer is in the layout engine, no?
untog 12y ago
I don't know how fundamental the problem is in terms of fixing it, but it is fundamental in making mobile webapps. I remember making an auto-complete friend selector a while ago (the kind that filters as you type) - I had the JS filtering through names in less than 10ms, but the resulting DOM updates immediately brought every keypress to around 400ms, which is visibly slow, and worse, laggy. I started work on a canvas-powered alternative before giving up - but I'm glad to see the React Canvas has gone with it. When I have some free time I'll be playing around with it to see if it lives up to the hype.
protonfish 12y ago
I write a lot of mobile web apps and find that the DOM is blazing fast. I wish I knew some examples of why people think that it is slow, but I have a few guesses. 1. Your mobile web framework is slow, not the browser DOM. Ditch your bloated frameworks - writing JavaScript without external libraries is not rocket science. 2. There are deliberate pauses in the DOM. The onclick event is very slow and unresponsive. I get very fast UIs by replacing it with ontouchstart 3. You are using too many animations. Smooth animations can work in mobile web, to a degree. But honestly, if the big reason nobody wants to do mobile web is because it doesn't support copious animations, I see that as a positive. I'd rather have a UI that just does what it should without having to wait through all the fanciness.
- danabramov 12y ago
  >I'd rather have a UI that just does what it should without having to wait through all the fanciness. Well, you would rather have it, just like some would rather have a Lynx-like interface. This doesn't address the point, which is users go to native because web just can't bring native-like experience.
  - Touche 12y ago
    Why is native-like better? Explain.
- cwyers 12y ago
  > But honestly, if the big reason nobody wants to do mobile web is because it doesn't support copious animations, I see that as a positive. I'd rather have a UI that just does what it should without having to wait through all the fanciness. Well, except native apps let you have those animations without waiting, is the thing.
- admyral 12y ago
  I'd love to see some examples of non-trivial apps written in pure JavaScript which: a) has decent browser compatibility b) is not a rat's nest of shims and polyfills c) could be maintained by more than one person
pothibo 12y ago
I often see native, iOS app being sluggish and I don't blame it on Objective-C or Swift. I blame it on the application. I don't understand how it's different when it comes to web apps.
reubenmorais 12y ago
DOM implementations have had vast improvements over the past years, vendors these days are working on nanosecond improvements to DOM operations. "The DOM is slow" usually refers to design problems that can't be optimized away, like being 99% synchronous, exposing APIs that invalidate layout at arbitrary times, etc. So yes, a fundamental problem that was exacerbated by the incredible advancement of JS engines over the last few years, causing developers to build more and more complicated web apps. To be honest, the fact that the DOM is as good as it is today is very impressive to me, considering how old it is and how much the landscape has changed.
tootie 12y ago
JavaScript is slow. DOM is really slow, but JavaScript is fundamentally slow. It's slower than Java and way slower than Obj-C and always will be. Excellent writeup here: http://sealedabstract.com/rants/why-mobile-web-apps-are-slow/ http://sealedabstract.com/rants/why-mobile-web-apps-are-slow...

kevincennis 12y ago

It depends entirely on what your app does – but yes, I'd paint this as a fundamental problem for any app that needs to render a large amount of content (and keep it updated).

danabramov 12y ago

>with all the advancement of the JS engines we'll hit a wall if the DOM does not start improving by an order of magnitude We already hit that wall a long time ago. DOM is the bottleneck in any non-trivial app (unless your app mines bitcoins or something).

shawndumas 12y ago
Agreed! Further, things like DOM diffing help but are an optimisation and can only take us so far. The answer is in the layout engine, no?

untog 12y ago

I don't know how fundamental the problem is in terms of fixing it, but it is fundamental in making mobile webapps. I remember making an auto-complete friend selector a while ago (the kind that filters as you type) - I had the JS filtering through names in less than 10ms, but the resulting DOM updates immediately brought every keypress to around 400ms, which is visibly slow, and worse, laggy. I started work on a canvas-powered alternative before giving up - but I'm glad to see the React Canvas has gone with it. When I have some free time I'll be playing around with it to see if it lives up to the hype.

protonfish 12y ago

I write a lot of mobile web apps and find that the DOM is blazing fast. I wish I knew some examples of why people think that it is slow, but I have a few guesses. 1. Your mobile web framework is slow, not the browser DOM. Ditch your bloated frameworks - writing JavaScript without external libraries is not rocket science. 2. There are deliberate pauses in the DOM. The onclick event is very slow and unresponsive. I get very fast UIs by replacing it with ontouchstart 3. You are using too many animations. Smooth animations can work in mobile web, to a degree. But honestly, if the big reason nobody wants to do mobile web is because it doesn't support copious animations, I see that as a positive. I'd rather have a UI that just does what it should without having to wait through all the fanciness.

danabramov 12y ago
>I'd rather have a UI that just does what it should without having to wait through all the fanciness. Well, you would rather have it, just like some would rather have a Lynx-like interface. This doesn't address the point, which is users go to native because web just can't bring native-like experience.
- Touche 12y ago
  Why is native-like better? Explain.
cwyers 12y ago
> But honestly, if the big reason nobody wants to do mobile web is because it doesn't support copious animations, I see that as a positive. I'd rather have a UI that just does what it should without having to wait through all the fanciness. Well, except native apps let you have those animations without waiting, is the thing.
admyral 12y ago
I'd love to see some examples of non-trivial apps written in pure JavaScript which: a) has decent browser compatibility b) is not a rat's nest of shims and polyfills c) could be maintained by more than one person

pothibo 12y ago

I often see native, iOS app being sluggish and I don't blame it on Objective-C or Swift. I blame it on the application. I don't understand how it's different when it comes to web apps.

reubenmorais 12y ago

DOM implementations have had vast improvements over the past years, vendors these days are working on nanosecond improvements to DOM operations. "The DOM is slow" usually refers to design problems that can't be optimized away, like being 99% synchronous, exposing APIs that invalidate layout at arbitrary times, etc. So yes, a fundamental problem that was exacerbated by the incredible advancement of JS engines over the last few years, causing developers to build more and more complicated web apps. To be honest, the fact that the DOM is as good as it is today is very impressive to me, considering how old it is and how much the landscape has changed.

tootie 12y ago

JavaScript is slow. DOM is really slow, but JavaScript is fundamentally slow. It's slower than Java and way slower than Obj-C and always will be. Excellent writeup here: http://sealedabstract.com/rants/why-mobile-web-apps-are-slow/ http://sealedabstract.com/rants/why-mobile-web-apps-are-slow...