> what if further JS will intersect with TS syntax
A core value of TypeScript is to support the latest ES20xx standard. The TypeScript team pays attention to JavaScript proposals. In the unlikely event that JavaScript got a type system, it would almost definitely be either TypeScript or Flow. If it wasn't, or if ES standards overlapped with TS syntax, then TS would remove that syntax.
Also, if you don't like the next version of TS, you can just use the old version to transpile your code and then stop using it. Switching to TS is an easily reversible decision, whether it's 1 day or 1 year later.
> We need clean break with transpile step (eg. Dart) or annotations.
You can already have this with Scala.js or any of the other languages that compile to JS. TypeScript is one option among many.
The appeal of TypeScript is that it fixes some things about JavaScript rather than throwing the language away. That's useful because it allows teams to transition from one to the other gradually. Facebook had to do the same thing with PHP, so they created Hack.
So there is no hard promise of TS backward compatibility ?
Sorry but whole TS looks like another EEE - MS will/can argue on some further JS changes for/against based on existing TS codebase. I hope I'm wrong here though.
You want to have your cake and eat it, too. You've just argued for both viewpoints (TS is bad because it does X and because it doesn't do X).
Just be honest and recognize that you dislike Typescript and/or Microsoft. Nothing to be ashamed of, many decisions in tech are based on feelings as much as on cold, calculated decisions.
What? I want TS to be different lang transpiled to JS or be annotation to JS but it is: Embrace and extend existing Standard (superset) and when everyone will write TS it will come to Extinguish step. (I like C# and don't like Windows my like not like to MS tech is 50%)
Microsoft is on the Javascript standards committee. So is Google, which is using TypeScript heavily in Angular 2.0. I would expect that TypeScript and JavaScript are going to continue to be harmonious.
It's very likely that JS will adopt some things tried initially in TS. Both TS and Babel have implemented extensions to the class syntax, for example, which are being considered for JS-future.
