Software Engineer at Google
One TypeScript / Angular 2 code health recommendation at Google is how to simplify dealing with RxJS
Observables. Two common options in Angular are subscribing to an
Observable inside of a Component's TypeScript code, versus using something like the
foo | async) from the template html. We typically recommend the latter for most straightforward use cases (code without side effects, etc.)
I typically review a fair amount of Angular code at work. One thing I typically encourage is using plain
Observables in an Angular Component, and using
foo | async) from the template html to handle subscription, rather than directly subscribing to an observable in a component TS file.
Subscribing in components
Unless you know a subscription you're starting in a component is very finite (e.g. an HTTP request with no retry logic, etc), subscriptions you make in a Component must:
- Be closed, stopped, or cancelled when exiting a component (e.g. when navigating away from a page),
- Only be opened (subscribed) when a component is actually loaded/visible (i.e. in ngOnInit rather than in a constructor).
AsyncPipe can take care of that for you
Instead of manually implementing component lifecycle hooks, remembering to subscribe and unsubscribe to an Observable,
AsyncPipe can do that for you.
#Typescript #Angular #RXJS #Async #Frontend
Michael Xin Sun
Software Engineer at Google Inc
Comment from HackerNews (https://news.ycombinator.com/item?id=8998736)
This is how Google Inbox and Google Spreadsheets works. See the slides from my recently produced GWT Create Session (http://t.co/ZvoaHxCoZT). J2ObjC slide deck here (https://docs.google.com/presentation/d/1mW_Plm5jAygELf7qjVK7...) Videos of the conference will be online soon.
Prior to that, some 20% Googlers also produced the PlayN library (https://github.com/threerings/playn) This was taken over by Michael Bayne who added an iOS backend by Bytecode -> IKVM -> Mono conversion. I beleive j2objc and RoboVM backends exist now as well.
The major benefit of the j2objc approach is the avoidance of GC in favor of ARC, the conversion of message-sends into C-method calls when possible, and integration with existing iOS toolchain.
When we started, it seemed like an iffy idea, but after developing a product delivered to millions of users on a high volume site (gmail) that has 70% code sharing, and being able to simultaneously develop, test, and deploy across the platforms reasonably efficiently, a lot of skeptics have become converts to the concept. JUniversal