Warning: These views are highly oppinated and might have some slightly incorrect facts. My experience with typescript was about 2 weeks in Node and a week in angular2.
TypeScript is implementing their own take on JavaScript. Some of the things they are writing will likely never make it in an official ES* spec either.
Technologies that have competing spec / community driven development have a history of failing; take: Flash, SilverLight, CoffeeScript, the list goes on. If you have a large code base, picking TypeScript is something your going to be living with for a long time. I can take a bet in 3 years JavaScript will still be around without a doubt.
Its also worth noting that they have built some things like module system and as soon as the spec came out they ditched it and started using that. Have fun updating!
It should also be worth mentioning that this language has been around for a long time and only recently gotten popular because of Angular2.
There is no community really driving the language itself. From what I see, random new things end up there with little to no community feedback. I could be wrong here, but I just don't see it much.
Its like trying to fit a square into a circle hole. A lot of the ES6/7 things I try to do don't work at all and will likely never work with the way some of the types work. I think it should be JS first and then types not the other way around.
It probably doesn't help that the main people that wrote this weren't big JavaScripters before they started but thats just my personal thought.
Babel is the ****! The plugin architecture system is amazing idea! I love being able to get community driven plugins ( Even if they might not be standard thats the risk I accept and am ok with ). I can target multiple environments ( node 4,5 / browser ). Plus, they are implementing specs and even if they are stage-0 and change, they are atleast some spec and i can run that plugin until I can update too.
I've been watching some of the targeting issues and they are pretty far out, TS on Node seems like a great fit, why not get that going asap?!
Babel is just SOOO far ahead ... The fact that people are using Babel and TypeScript together is a huge flag that TS needs to up their game.
Um, why do I need to mock fake TSDs for things that aren't TypeScript!? Your creating more headache, work, etc. This should have been addressed in v0!
I hit this all the time, I had no idea what ES* features I could use and what I couldn't. I spoke about this on a issue and they said they are only doing stage-3 but they have other things that are stage-0?
I think I've heard about 100x you can use as much or as little of it you want. Ya, good luck. Having to put any everywhere is not my idea of that statement.
I do generally like the approach FlowType is taking.. they put JS first and then lay types on top. Also, I can use babel to compile it and its not as much of a plunge into a java/c# like language.
TS and Babel are doing similar type declaration syntax so its a safer bet that might be included in a upcoming spec and if it doesn't you can always use babel-remove-flow-types ;).
because javascript is not a functional language. javascript has no tail call recursion, so sooner or later you will hit the "maximum call stack size exceeded" error, and the function call overhead makes functional style slower and more memory-hungry than imperative style... but you can implement lazy functions and trampolines in javascript, and some functional languages are hosted on javascript, like clojurescript