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Is ReactJS really fast?

blog.500tech.com

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Re: Is ReactJS really fast?

#21

Post by phillmv »

We need to stop this cargo cult stuff.

"Speed" as determined by rendering stuff to a page is actually something we can determine. Is it not possible to simply trace the framework execution? What's the point of having silly hype pieces back and forth when we're debating trivial examples that ought to be not too difficult to measure?

Finally, wrt to React: it's just a view layer. Comparing it to Ember or Angular as if it were a fully fledged, swappable alternative doesn't really make sense.

Re: Is ReactJS really fast?

#22

Post by aikah »

whoisthemachine wrote: post #4

The basic premise seems to be that AngularJS can be just as performant as ReactJS if you do your homework and avoid common pitfalls of AngularJS. I would argue that the beauty of ReactJS is that it doesn't have any gotchas. It's performant without needing a deep knowledge of the framework.

> The basic premise seems to be that AngularJS can be just as performant as ReactJS if you do your homework and avoid common pitfalls of AngularJS.

While AngularJS(1.x) is a bit faster now, your comment is a bit like saying Ruby can be equally fast to Java if one does it homework.

AngularJS has architectural problems that can only be reduced if one doesn't use much of angular features(scopes,watches) inside directives(which means writing components in pure js). So it takes a huge effort to make angular fast in general. That's the reason why they are creating an entirely new framework with version 2.x (which I believe is a mistake, Angular 1.x despite its flaws was pragmatic, 2.x isn't).

React is faster for a few reasons: there are no templates in react, everything is js code React does all the heavy computation outside the DOM so manipulations are minimal and there is no two-way data binding by default, the data flow is unidirectional.

Obviously the angular team wants the same stuff since it has proven it is a better architecture.

Re: Is ReactJS really fast?

#23

Post by egeozcan »

Virtual DOM diffing (the approach taken by React) is "faster" because, in the most simplistic definition, you can intuitively come up with the optimization mentioned in the article as it needs to know what exactly changed to calculate. What's good with React is that it does some of it automatically (with the keys and the structure you have to provide) and also gives you control with the "shouldComponentUpdate" method.

Edit: Down-voters care to comment?

Re: Is ReactJS really fast?

#24

Post by mrharrison »

From other devs I know they have said React functionality on mobile is quite poor. Drag and drop and scroll, doesn't work as well, because the virtual DOM isn't adapted work to well on mobile. So for that reason, I won't use React, and rather go Vanilla or use Backbone. After getting burned by Angular, I'm really weary to adopt another fancy framework.

Re: Is ReactJS really fast?

#25

Post by grayrest »

The most important thing about React's update performance is that it's ~O(n) of the size of the virtual dom. If React's performance is a problem you can window the input data, do things more efficiently in your render, tweak shouldComponentUpdate. The goal isn't to be as fast as possible but rather to be fast enough and for non-mobile you can hit that target with only the occasional tweak. For mobile, you can get as exciting as you like[1] but I've never had to go beyond the above steps.

[1] http://engineering.flipboard.com/2015/02/mobile-web/

You can build things that are faster than React in benchmarks. Pretty much every vdom based library/framework/language is faster than React in benchmarks and absolute performance has never been a stated goal of the project. The framework does help you out in ways that don't show up on benchmarks like this. An example would be batching DOM updates, which is much harder when you have components mucking around directly with their internal set of nodes.

I also favor using an immutable data tree with a corresponding shouldComponentUpdate and only rendering on rAF but those force architectural decisions on the project.

Re: Is ReactJS really fast?

#27

Post by iSnow »

feedjoelpie wrote: post #13

React.js is actually just really pleasant to work in and easy to reason about, and the virtual DOM is what makes that all possible without it becoming unacceptably slow. DOM diffing isn't there to make React faster than everything else ever imagined. It's there to let you stop thinking about the DOM and focus on the world state of your frontend instead. I wasn't truly interested in React until I read this, which does…

The author however has focused specifically on the often read speed advantages. They use it themselves and he apparently likes it.

Re: Is ReactJS really fast?

#28

Post by manishsharan »

I have been using Backbone + moustache/handlebar templates and I am not clear on why use a virtualDOM. My application has several views and in my views, I use events to sync data model changes with the view and the view's render function maintains the DOM element . None of my views have to deal with the whole DOM. Therefore, I am really confused. So with my apologies for asking a dumb question : why maintain the whole virtual DOM? And what am I missing with Backbone + mustache based approach ?

Re: Is ReactJS really fast?

#29

Post by feedjoelpie »

iSnow wrote: post #27
feedjoelpie wrote: post #13

React.js is actually just really pleasant to work in and easy to reason about, and the virtual DOM is what makes that all possible without it becoming unacceptably slow. DOM diffing isn't there to make React faster than everything else ever imagined. It's there to let you stop thinking about the DOM and focus on the world state of your frontend instead. I wasn't truly interested in React until I read this, which does…

The author however has focused specifically on the often read speed advantages. They use it themselves and he apparently likes it.

I guess the point I'm getting at is that the virtual DOM's speed is really just the answer to the question "But isn't re-rendering the whole world over and over really slow?" Which is the first thing anyone deeply familiar with web UIs would ask.

It's the solution to a problem that arises when you move to this programming model. It's the programming model that's the real advantage. The virtual DOM's speed is worth mentioning because it remedies what would otherwise make React completely impractical in the real world.

Re: Is ReactJS really fast?

#30

Post by niix »

The final point of the argument is the best to me. I originally chose using React because it appeared different from everything else. Thus far I feel I have been able to be much more productive and also think about things in my web application differently. The fact that is it fast is only secondary to the fact that I feel I can great a robust and maintainable codebase with more ease than I could with other frameworks.
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