Hacker News Reader

Comment by rattray | Hacker News Reader

Why not React / React Native?

If i understood it correctly, React Native basically gives you a JS runtime environment that handles communication with native APIs of the system and is shipped with your app. Flutter (and Dart) will transpile into native code and compile natively for your platform.

So on React Native you will have that abstraction layer add runtime latency and package size of your app, while Flutter (Dart) really outputs native code.

Flutter gives you native code but not native UI. It reimplements and draws everything itself (mimicking the native look), like Swing or Qt.

React Native is the other way around - real native widgets backed by interpreted/jitted JavaScript code.

When React Native's fabric rearchitecture is available you will see much better performance. The thing that hurts performance today is that damn bridge communication between javascript and native that will be severely improved in fabric.

As I understand it, Flutter/Dart is compiled to native code but not using any of the native UI widgets.

To get native code plus native UI widgets plus some cross platform reuse you'd have to go with something like Xamarin.

Package size for Flutter apps is a lot larger than RN, even the RN Android build that ships it’s own JS runtime. There are complaints everywhere of simple apps reaching 100MB size.

As for runtime latency, I’ve recently worked on a RN app that outperformed its native sibling. Looking forward to the Fabric release.

Unless you're importing a ridiculous amount of packages and assets, you'd never hit 100MB with simple apps, that's just people looking at debug mode and thinking that it's the final app size. Simple apps can easily be under 8MB once compiled.

Not really true, you are likely comparing a debug build. An Android Flutter apk sits around 4MB for smallest app. Most of my apk sizes are around 8MB-10MB w/ Flutter

I haven't written any myself, going from reports online that builds are a lot larger than expected. That minimum size is for an app without any components or other modules. The RN app I mentioned was ~6MB with a fully blown app, state management, heavy data layer, hundreds of components, animation, i18n, a handful of native modules, encryption, and so on.

In short, Flutter doesn't really have any advantage in size over RN.

React Native has a JavaScript layer that hurts performance and it is not truly native as they say. Just do a reach on flutter vs react native and you'll see better explanations and comparisons.

I’m not sure this really matters for a lot of things anymore. Sorting a few hundred text items in a list, for example, is going to be so fast on modern smartphones that it will not make much of a difference whether it’s done in JavaScript or native.

Maybe a poor example, but I suspect the only times it really makes a difference is significantly computationally expensive tasks

so? most apps are by nature going to be computationally expensive if they want to compete/successfully use all phone features. i made a simple(according to them) corporate data sync app recently and the company wanted a laundry list of features - background sync, smooth scrolling of extremely large datasets, photographic analysis of images taken at tolls(extracting license plate information/classifying vehicles automatically for tracking).

All of this had to be made in a performant way so as to run on phones with 1 gig of ram as the company was giving phones to everyone specifically for just this purpose(and general communication ofc).However it also needed to work on iphones/windows phones(old ones the execs purchased en masse)

Xamarin was the only choice att as react just doesn't work stably on windows phones but i'm excited to see the future

Your app sounds like it used some advanced features, but I don’t think most apps are going to be computationally expensive in the way that local-AI, image processing, or crypto activities might be. I am not sure what qualifies as extremely large datasets, but I’d be surprised if keeping a few dozen objects in order is significantly lower in JS than Swift. Yes, it may be an order of magnitude slower - or ten orders - but that seems negligible if the total time for processing is still nanoseconds. Guess it always comes down to the task at hand.

When I made the decision in December:

Preference for Dart over JS (lots of reasons, involving language, package manager, compiled performance)

Predictable UI behaviour across devices, OS versions, platforms. As long as you handle presence/absence of device features, and build your UI to scale properly, it behaves as you would expect, everywhere. The value of this cannot be overstated enough.

Future opportunity for code sharing with non mobile platforms. Even without Flutter-web, I could still compile the business logic part of my code to JS and use it with another UI (similar things can be done with React).

Reply on news.ycombinator.com