Recently, I evaluated some modern tools to build an SPA (single page application).
The forerunners were Dart + AngularDart, or Dart + Polymer.dart.
In the end, though, I actually went with AngularJS, which wasn't even on the original list.
The major knocks against Dart + {AngularDart,Polymer.dart} was simply that they both enforced use ShadowDOM. Polymer had recently taken out "applyAuthorStyles" as well as the "lightdom" attribute, and AngularDart's templates are based on ShadowDOM.
While that's fine for some hobbyist stuff I might do with Dart, I am definitely not interested in playing with ShadowDOM when I'm trying to quickly iterate an application. I don't have the resources to constantly reinvent components -- Bootstrap, for instance -- at every step of the process.
I understand the uses of ShadowDOM, but they just don't apply to most of the work I do. I'm not building generic widgets for everyone to use across the web, I'm building them out specifically for a particular application. Maybe they're generic enough they can get slurped out -- fine. But at the time of me writing them, I'm interested in getting them working as quickly as possible.
If I had a dedicated designer who would do all the work of crafting everything from scratch, I may have been more inclined to pick AngularDart... but then I would just be moving the burden to them instead. Either way it's still an unnecessary use of resources, especially in 2014, when you can cobble 50% of your webapp together with off the shelf components.
I suppose I could have just used "regular" Dart and some additives, but I'd be pretty unproductive, and in the end I would have something that looks like a bastard child between Angular + whatever, with nothing to show for it other than a lot of wasted time[1].
My days of reinventing the wheel were over years ago.
All that said, AngularJS has turned out to be very nice! I originally started with plain old JavaScript, but recently transitioned to CoffeeScript; productivity has improved significantly and the code is much more readable.
I've never had a problem with debugging the generated JavaScript in DevTools or Firebug, which is a complaint I hear alot about CoffeeScript. I suspect a really old versions of CoffeeScript produced some hard to read JavaScript, and that the meme still lives because, well, this is the Web and nothing really dies here.
[1]: A project I once worked on was based off Sinatra instead of Rails because the team lead said it was "lighter." I looked at the codebase and it was basically a bastardized version of Rails: they pulled in most of the active* gems, and had half-assed "url_for" constructs that looked similar to their Rails counter-part but functioned completely different in certain ways. Developing against that codebase took forever. In some down time, I prototyped porting it to Rails proper, and it was about as fast as the Sinatra version...
