Introducing React Native [video]

I wish they'd go into more detail on why they can't make an app like paper in the browser environment. They mentioned something about Web Workers being crippled and later on explained how their framework puts JavaScript in it's own thread by default.

I'm also wondering why in their experience no one ever comes close to native widgets when imitating them in a Web apps.

TL;DR to below: focusing on JS instead of Xaml seems like a smarter play for a .NET developer that hasn't used Xaml in WPF or SL previously.

I put "web oriented .NET developer" in my response for this specific type of question. I kind of defaulted (11 years ago) into ASP classic and ASP.NET as a result of ad hoc consulting/support work for MS technologies back in 2000. But despite my affection for C# I abandoned ASP.NET's faux desktop event driven emulation for MVC as soon as it was released. Ever since then I felt sort of stuck in between thinking of myself as a Web Developer vs thinking of myself as a .NET Developer.

Which brings my long winded response back to your original question about WPF and data binding. WPF and Xaml are pretty foreign to me (I still have no idea about how WPF/SL/WinRT Xaml differ it all seems like Xaml to me) despite a long history with C#. But I am interested in native app development, so I have been torn on whether to go all in with C# knowing I could take it cross platform with Xamarin but need to reorient myself into the Xaml world or go all in with HTML5 knowing Cordova could be "mostly good enough".

I'm a Microsoft fan (I actually enjoy my Surface RT and Windows Phone) so WinJS on Windows 8 seemed like a good hedge for not throwing away all my JS knowledge (which is becoming a predominant part of my work with SPAs) but still letting me go fully native. But the overall Windows dev community seems to have spoken, Xaml is it and WinJS is a pariah, MS doesn't help much by staying mum on the matter but I think they are trying to shove WinJS into the Cordova camp and double down on Xaml for Win 10 with WinJS eventually fading away.

with gpu-accelerated css transitions, requestAnimationFrame, virtual dom and web workers, the experience can be damn close. he makes it seem like "no comparison", this is provably false at least for the apps he demoed. for games, native is still necessary. what react offers beyond performance though, is definitely awesome.

imo, the talk comes off a bit like a sales pitch at a pep rally.

> Web Workers being crippled

As Tom said, you can't do layout or prerendering-to-bitmap in a web worker: there's no DOM or Canvas API unless you bring your own, and despite Emscripten it's foolhardy to bring your own. If you want to decode a JPEG, you have to do that on the main thread and pass it to the worker right now (except in Firefox with its nonstandard ImageData API). [0] Which brings us back to square one.

> no one ever comes close to native widgets

I think a lot of that has to do with the fact that the iOS UIKit internal code for animations is closed source - the best anyone can do is reverse engineer, move their thumb and see how things react. What are the Bezier points on the curve used for the fade when you "back-swipe" from the left of the screen? Good luck figuring that out - it's possible, but only barely. Tom hinted at the idea that if developers were better organized, they might be able to replicate things better, but it would still be an uphill battle.

[0] https://developer.mozilla.org/en-US/docs/Web/API/Worker/Func...

There's quite a bit of hyperbole in this talk. Some web apps do in fact come close to native, but to the trained eye of a Facebook software engineer it will feel miles behind. Your average Joe doesn't give a shit, as long as they can use the app. If they did, Facebook's Paper wouldn't have been such a flop.