TypeScript: a language for application-scale JavaScript development

http://www.typescriptlang.org/

by D_Guidi • 14 years ago

474 298 14 years ago

TypeScript is a language for application-scale JavaScript development. TypeScript is a typed superset of JavaScript that compiles to plain JavaScript. Any browser. Any host. Any OS. Open Source. From Microsoft.

lukeholder• 14 years ago

Can I write my TypeScript in coffeescript?

gfosco• 14 years ago

One can never be too careful, apparently.

streptomycin• 14 years ago

This seems similar to the type checking and optimization done by Google Closure Compiler?

polarix2• 14 years ago

The main difference is that the Closure compiler compiles JS->JS, keeping all the type info in jsdoc comments. Typescript makes the typing a first class language entity, which reduces code portability (and toolchain flexibility) in favor of (I assume) readability and maintainabilty.

Another huge advantage is that the typescript parser & compiler is written in Javascript. Closure's jscomp is Java, which decreases backend portability somewhat.

cek3• 14 years ago

Say what you want about whether this is a good idea or not, it is clear at least part of MS is really serious about open source.

* TypeScript is under the Apache 2.0 license [1]

* Source is available via git on Codeplex [2]

* Installation is as easy as npm install -g typescript [3]

Extra bonus coolness: They've provided an online playground like jsfiddle! [4].

[1]http://typescript.codeplex.com/license

[2]http://typescript.codeplex.com/SourceControl/changeset/view/...

[3]http://www.typescriptlang.org/#Download

[4]http://www.typescriptlang.org/Playground/

kibwen• 14 years ago

Also cool: in addition to the expected Visual Studio support, they've also provided support for Sublime Text, Emacs, and Vim.

http://blogs.msdn.com/b/interoperability/archive/2012/10/01/...

caseyohara• 14 years ago

Sourcing typescript.vim throws errors: http://pastebin.com/raw.php?i=HHDJDG7X

nigma• 14 years ago

The online playground can do live syntax and type checking as well as provide function call hints. That's pretty cool.

PabloOsinaga• 14 years ago

and you can also see in realtime the typescript -> javascript compilation as you type your typescript code. pretty cool.

DougWebb2• 14 years ago

I started doing C# development last year, coming from mostly a Unix/Perl platform, and I'm really glad about the timing because that's when Microsoft got serious about open development. I started doing web apps using ASP.NET MVC3, and this year MVC4 was released as an open-source project[1]. It seems that a bunch of 'young turks' have reached higher management positions in most of the key software development products within Microsoft and they're all pushing for this kind of open source approach.

[1] http://aspnet.codeplex.com/

skrebbel2• 14 years ago

Roughly the same story here. At the risk of sounding like a fanboy, I feel that while most tech BigCos (e.g. Google, Apple) have become more evil over time, MS has actually become less evil, to the point that using their tech (and some major tech at that) is relatively free of any lock-in risk.

TypeScript seems very much in line with this trend, and I love it. This is exactly what I wanted - JavaScript but with decent safety and IDE support. And no more than that. I really hope that non-MS-geeks will embrace it and that Eclipse plugins and JetBrains tools and the likes will follow.

That said, ASP.NET MVC is a misguided and overrated Rails ripoff, IMHO. Where's all that great refactoring support if everything is made `dynamic` and stringly typed? What's up with matching parameters to method argument names? (I mean, change an argument name and your code breaks? wtf?) Since when does Microsoft tech favour magic over clarity?

shawnb576• 14 years ago

Interesting.

Worth noting that the Azure SDK [1] was released on GitHub over a year ago with the same attributes. The move to Codeplex is concerning.

[1] https://github.com/WindowsAzure/azure-sdk-for-node

jules• 14 years ago

Using their own platform instead of a commercial competitor that is also closed source is concerning?! Would it also be concerning if github hosted their open source projects on github instead of on codeplex?

chollida1• 14 years ago

> The move to Codeplex is concerning.

What's concerning about moving the location where Microsoft hosts their code?

eranation• 14 years ago

Microsoft is doing a lot of community trust building steps that I wish Oracle / Sun were doing, I wonder if people take it seriously and if Microsoft will be ever "Cool" again in the startup / hacker community, or is taken as PR attempts? I personally like it.

OriginalSyn• 14 years ago

I don't know when it happened but CodePlex got a makeover as well, it looks good.

JimmaDaRustla2• 14 years ago

Microsoft also has Github a account/accounts - I thought they were going use it for all their open-source projects, but they seem undecided now.

colin_jack7• 14 years ago

I have to admit I'm impressed with MS here.

Contrast Dart and TS. Dart announced a year ago and they're only now dealing the JS interop issue, so to most people its still only really interesting as a play thing. TS announced and from the looks of if we choose to we can immediately start using it.

I know Dart is more ambitious and maybe long term their focus on issues other than interop will be proved to be correct, but I doubt it.

discreteevent• 14 years ago

Google deliberately opened up dart development early. I thing that was a good thing. They could have kept it closed and released it today, it's roughly as mature as type script seems to be. Would you have been happier with that?

munificent4• 14 years ago

Comparing JS interop in Dart and TypeScript is apples and oranges. Dart has a native virtual machine with its own garbage collector and object representation. The language itself has an entirely different object model and set of collection types. For better or worse, even Dart's number types are different from JS. Doing JS interop in Dart is like trying to do interop between the JVM and CLR.

TypeScript doesn't have JS interop: it is JavaScript. TypeScript is basically JS linter with a type annotation syntax. (And a few additional local features like arrow functions and class syntax.)

That being said, we know on the Dart team that JS interop is hugely important. It's just much harder for us to do. We've just announced a big step in the right direction: http://www.dartlang.org/articles/js-dart-interop/

mtgx• 14 years ago

Only when it suits them. When it doesn't, they go after the companies using it with the threat of lawsuits.

hermanhermitage2• 14 years ago

This looks excellent a nice restrained effort. Hasn't fallen into the trap that ActionScript3 did with too much ceremony, and its nice to see a syntactic super-setting approach rather than Dart's.

Now what I'd like to see in Javascripts evolution (non backwards compatible):

    * Subract: Removing parts of the language - let crockford free to rip out the bad parts.
    * Enhance: Bring in some more taste of Scheme.
    * Replace: New scoping for var etc, without introducing new keywords.

jasondenizac2• 14 years ago

new scoping for `var`? Like the block-scoped `let`?

gcr• 14 years ago

What would more "taste of scheme" mean? Do you mean like lexically-shaped macros?

kombine2• 14 years ago

Now I want to take an advantage of strict typing at runtime, which is obviously not possible, because instead of standardizing a VM all vendors are doing stupid things like this.

cek3• 14 years ago

I'm willing to bet MS has built runtime type support into the Chakra VM.

The question is whether they will do it in a propitiatory way or push it as an extension of ECMAScript and try to get other VMs to implement it.

kombine2• 14 years ago

The worst thing is that they already have the runtime that is language-agnostic, performant, has a great standard library and so on. When they tried making it available on the Web, the so-called "open stadards" won. Which are in fact a bag of shit.

freehunter• 14 years ago

On the Techcrunch article also posted to HN recently, the designer said they would not be baking TypeScript into Chakra, but rather letting it compile to JS and running it the same way everywhere.

untog6• 14 years ago

The TechCrunch[1] article states otherwise:

"Asked whether Microsoft might do something to prioritize TypecSript in Internet Explorer, Lucco, the chief architect of IE’s JavaScript rendering engine Chakra, says no."

[1] http://techcrunch.com/2012/10/01/microsoft-previews-new-java...

swannodette• 14 years ago

They've added type annotations to all of jQuery it seems?

http://typescript.codeplex.com/SourceControl/changeset/view/...

iambot• 14 years ago

I worked on a joke/conversion project a little while ago that achieves the same ends without having to compile to JavaScript.

The only reason I wrote it was to prove to a co-worker who was "hating" on JavaScript that it IS possible to have a type system in JavaScript - if that's what you want. Its not the same end result but similar enough to warrant a mention.

Here's the repo: https://github.com/christopherdebeer/TypedFunc

MicroAndMacro• 14 years ago

Sublime Text, Vi, Emacs: TypeScript enabled http://blogs.msdn.com/b/interoperability/archive/2012/10/01/...

tlack3• 14 years ago

Weird that I didn't spot a friendly list of features.. seems to have some cool ones, like a shortened function expression (from the doc PDF):

    (x) => { return Math.sin(x); }

and modules, which are implemented using the immediately invoked function expression pattern:

    module M {
      var s = "hello";
      export function f() {
        return s;
      }
    }

Syntax seems more clear than CoffeeScript and tool chain will probably shape up better. Looking forward to seeing this get some traction.

untog6• 14 years ago

I like the shortened function form. I played around with CS for a while before going back to JS, but I do miss being able to do something like:

    var names = people.map((p) -> return p.name);

(or something along those lines). Funnily enough, it reminds me of C#'s LINQ:

    var names = people.Select(p => p.name);

tlack3• 14 years ago

Apparently ECMAScript 6 is considering some other forms of function literals as well: http://www.2ality.com/2012/04/arrow-functions.html

wingspan22• 14 years ago

I've written a LINQ style library for TypeScript that allows you to write something like this:

  from([1,2,3]).select(n => n * n).where(n >=2).toArray()

which outputs

  [4, 9]

Hoping to open source it soon.

Edit: typo, n * 2 should have been n * n, sorry for the confusion

baltcode• 14 years ago

It's actually even shorter:

      names = people.map((p) -> p.name)

wingspan22• 14 years ago

Here are some off the top of my head:

1. Lambdas (as you mentioned) are not only shortened syntax, but also capture the `this` variable automatically for you. Try typing in the following at the playground in the body of the `greet` method to see what I mean (http://typescriptlang.org/playground):

  var x = a => this.greet();

2. Classes with inheritance are a big one, implemented using the IIFE pattern as well, with support for static and class members.

3. Interfaces with duck typing are very lightweight and easy to use:

  interface IGreeter { greet(); }
  class Greeter /* implements IGreeter */ {
      greet() { ... };
  }

4. Extensive type inference. In the following example, the function greet will be typed () => string:

  class Greet {
    greet(x: number) {
        var s = ' greetings';
        return x + s;
    }
  }

Static and member vars, return types, local variables, all are type inferred.

5. Javascript is TypeScript, just without typing, so converting your codebase is instance, and then you can begin adding type annotations to get more robust checking

koops• 14 years ago

I've written a lot of JavaScript, including large-scale projects, and never once have thought, "Gee, I wish I had type checking."

Haven't we come to a consensus that types are more trouble than they're worth? They hurt clarity and catch few bugs.

masklinn4• 14 years ago

> Haven't we come to a consensus that types are more trouble than they're worth?

Pretty sure we haven't. That shitty languages with shitty type systems are mor trouble than they're worth yes, but types?

ovidiu2• 14 years ago

No, we have not. Read John Carmack's posts on static code analysis to understand why.

erichocean2• 14 years ago

I've been writing large-scale JS applications with SproutCore since 2007, and not once have I been bitten by a bug that would have been caught by static typing.

Same with Objective-C and my iOS and Cocoa development (since the OpenStep days).

I do use Scala on the server side though, and it helps there. But application development is, IMO, hindered by static typing. It's a lot more work to set up, and provides essentially zero benefit.

And I love static type analysis (I use it with C stuff all the time). +1

bruceboughton• 14 years ago

Like spaces vs. tabs, braces vs significant whitespace, there is, and never will be, no such consensus.

jakejake3• 14 years ago

I have a theory about this - how you feel about static typing is related to whether you see the compiler as your friend or as your enemy.

If you see the compiler as your friend then you tend to like type checking because it blocks certain bugs and typos. It won't let you run your code until they're fixed. If you see the compiler as your enemy, as a barricade that you need to get past, then you tend to not like static types. The compiler prevents you from seeing your code running immediately.

Obviously there's other benefits to each system but I feel like this is the more "gut reaction."

airfoil• 14 years ago

Ha! I think you may be on to something. I've always had a "fear of rejection" with the compiler and I tend to get more enjoyment when coding in Python, Lisp, etc..

masklinn4• 14 years ago

> I have a theory about this - how you feel about static typing is related to whether you see the compiler as your friend or as your enemy.

An alternative explanation is a dislike of overly verbose languages with terrible type systems (the poster child for this category being Java), and as a result of low exposure to better statically typed languages painting all of the category with a Java brush.

colin_jack7• 14 years ago

Not really, i love JavaScript but do think types have their place in documenting the code and in supporting tooling (e.g. Refactoring).

drcode2• 14 years ago

Back in the day, Microsoft would use a strategy called "embrace, extend, extinguish." http://en.wikipedia.org/wiki/Embrace,_extend_and_extinguish

Recently, Microsoft has been pushing Javascript very hard (embrace) and now it looks like they've started the "extend" phase.

Luckily, no one really worries about them being able to pull off the "extinguish" part anymore... they just don't have enough market power these days.

EDIT: Yes, I conceede the fact that TypeScript is OS probably addresses most of these objections.

zokier2• 14 years ago

TypeScript is as likely to extinguish JS as ASP is to extinguish HTML.

MatthewPhillips• 14 years ago

You're wrong "extend" is when you add features to a standard that are not part of the standard. Since this only compiles to JavaScript and isn't being built into IE, it doesn't qualify. Dart does, though.

untog6• 14 years ago

Except that this is fully open source, which makes it a little difficult for MS to retain control over it, no?

Re-reading late 90s M$ memes gets old after a time.

drcode2• 14 years ago

good point.

dj2stein9• 14 years ago

Microsoft was so ruthless, and dominating in the 1990's that it will be incredibly difficult to convince any developer that was streamrolled by this company to give them a second chance.

jakejake3• 14 years ago

This would still be the "embrase" phase. Extending is when they add a new feature that doesn't exist and isn't supported by the competitors. As soon as you see it compile to a flavor of JavaScript that only IE understands - then will the "extend" phase have begun.

wingspan22• 14 years ago

Awesome, great to see this finally released. I'm a dev in FUSE Labs (http://fuse.microsoft.com) and we've been dogfooding TypeScript for a while now. I'd be happy to answer any questions about using TypeScript vs vanilla JS, converting a large codebase, etc.

ovidiu2• 14 years ago

I'm wondering how to make use of an existing object system. We already have a JS framework that simulates classes and inheritance in the Java-style OOP.

wingspan22• 14 years ago

If you have a small sample, you could try it out in the playground (http://www.typescriptlang.org/Playground/) and see what TypeScript can recognize. Generally, I've seen TypeScript plays well with other OO forms and gives you intellisense on quite a lot.

platonichvn2• 14 years ago

This is great to hear. I have only just started reading up on TypeScript. But I would love to know if there will be support for a decimal type. I have been following Google's work on Dart and it doesn't look like they will be implementing it last I checked. Such a feature would be a great differentiator.

wingspan22• 14 years ago

A team member could comment better than I, but unless TypeScript adds some kind of operator overloading, supporting a new type would be difficult since it compiles to normal JavaScript. Even then, creating a performance decimal type without native code support might be difficult.

lstroud• 14 years ago

How does it compare to Dart & Harmony (even coffeescript)?

I know that is a long answer, but I'd love a bullet point list of how if compares to the other javascript++ languages that have been coming out over the last couple of years.

wingspan22• 14 years ago

I'd have to defer this one to the language designers, I'm sure they've done such a comparison.

Per the spec [1]:

  TypeScript syntax includes several proposed features of Ecmascript 6 (ES6), including classes and modules.

[1] http://go.microsoft.com/fwlink/?LinkId=267121

zachrose2• 14 years ago

Would it not be just as reasonable to put type information in JSDoc, and build a preprocessor that does the complaining?

ericcholis• 14 years ago

Favorite part about this, I didn't know it was Microsoft until I scrolled down!

lowboy4• 14 years ago

I had suspicions from their choice of styling and typeface.

init0• 14 years ago

http://i.imgur.com/XB3ib.png Oh M$ Oh...

untog6• 14 years ago

You lost me at "M$". I'd like to think that HN's level of discussion is above that.

cbaleanu2• 14 years ago

Nonetheless, interesting disclaimer text spotted there. Raises a good question... would that text be there because somebody in the industry analyzes your code?

spicyj5• 14 years ago

This looks nice. I love the fact that there's no runtime that needs to be included or any overhead when the compiled JS runs.

It'd be 100% more useful if it was more aware of nullable types -- as it is, it appears that

    null * 7

compiles without any error messages. If they add a "nullable number" type distinct from "number", I'll be a lot more likely to use it.

It also appears that some other things compile that perhaps shouldn't, such as

    7[2]

and

    7["a"]

even though (7).a is equivalent and (correctly) fails to compile.

wingspan22• 14 years ago

`7[2]` is valid Javascript, so it is also valid TypeScript (fetching the '2' member of the `7` object).

Detecting null expressions at compile time might help. There are "nullable" types, but afaik only in signatures:

  foo(x?) {
      alert(x);
  }

If `x` is not passed in, it will be `undefined`.

spicyj5• 14 years ago

"wingspan" * 7 is also gramatically correct JavaScript, but evaluates to NaN and almost certainly isn't what you want in your JS program, which is why TypeScript prints a type error (well, warning) if you try to compile it.

Having optional variables is similar, but not the same as nullable types, especially when the compiler can't enforce non-nullable-ness. All JS devs are familiar with the annoying error "'null' is not an object" (and anyone who's programmed in a language like Haskell, OCaml, or F# knows the value of sophisticated compile-type type checking).

wicknicks• 14 years ago

Looks really good. The IDE support looks like a big bonus. Wish this had been released on a Friday -- have to wait a bit before I can dig deeper!

tlrobinson3• 14 years ago

This looks great, but the IDE seems to be one of the key features, so we're going to need something other than Visual Studio.

EDIT: they've got syntax highlighting for some other editors, but full completion and error reporting is still needed http://blogs.msdn.com/b/interoperability/archive/2012/10/01/...

jopamer• 14 years ago

Our language service APIs are all open source, so feel free to hack together support for your favorite IDE and let us know! (Check out the code under src\services, and let us know if you have questions.)

Permit• 14 years ago

I can't imagine it'll be too tough for other IDEs to support.

There's a pretty impressive demo here: http://www.typescriptlang.org/Playground/

It even has auto-complete if you press "Ctr-Space" while typing a word. Considering the source for all this stuff is freely available, I don't think it'll be too long before other IDEs support it.

wingspan22• 14 years ago

The language support in VS is really great, and getting better with each release. Go to definition, code outlining, folding, type information on hover, intellisense; all these make writing code much less easier and error prone, especially if you are used to writing in a language like C# or Java in a good IDE.

tlrobinson3• 14 years ago

But does VS run on Mac OS X or Linux? Didn't think so.

wensheng• 14 years ago

No list comprehension? No, Thanks.

wingspan22• 14 years ago

Would be a good thing to suggest to the team, it is the first release of the language, after all.

In the interim, a simple library like underscore is quite succinct:

  _.map([1,2,3], n => n * n)

With more library support you could even do infinite lists with something like this:

  _.generate(index => 1.0 / index);

mykolasmith• 14 years ago

Codeplex/samples/simple (http://bit.ly/Svcc4Y) is the same as the CoffeeScript constructors doc section (http://bitly.com/PnLtGy)... Wonder what other stuff they borrowed from CoffeeScript?

nagnatron• 14 years ago

Maybe that's a good idea because it makes it easy to compare the two?

jonny_eh• 14 years ago

I was reading the synopsis on the page then it faded out and replaced it with sample code. Geez, let me read and then scroll down. WTF is with the carousel non-sense?

scanr2• 14 years ago

Very interesting. The Apache 2.0 Licence is comforting, makes it worth having a look. The docs are here for anyone interested in the spec:

http://typescript.codeplex.com/documentation

I like what they've done. Nothing too revolutionary, mostly adding static typing to Javascript without straying to far from the existing (or future) language or increasing the noise significantly.

Here's some highlights:

* Type inference

    function f() {
        return "Hello World!";
    }

Will do the right thing

* Explicit Typing

    function f(s: string) {
        return s;
    }

* 'Ambient Types'

To facilitate integration into existing JS libraries or the DOM, TypeScript lets you specify 'placeholders' for variables / classes that the runtime would expect to see e.g.

    declare var document;

Almost a kind of dependency injection but also a neat way to manage talking to existing code.

* Structural Typing

* Classes and Interfaces

    interface BankAccount {
        balance: number;
        deposit(credit: number): number;
    }
    
    class CheckingAccount extends BankAccount {
        constructor(balance: number) {
            super(balance);
        }
        writeCheck(debit: number) {
            this.balance -= debit;
        }
    }

* Modules

    module M {
        var s = "hello";
        export function f() {
            return s;
        }
    }

* Arrow function expressions

    (x) => { return Math.sin(x); }

euroclydon4• 14 years ago

Are you actually implying with the above example code that you can call a undefined "super" constructor on an interface and pass it the "balance" variable, which the interface's non-existent constructor would presumably match by name?

scanr2• 14 years ago

Nope. I probably should have used a different example for the interface. The examples are from the full spec where they progress a little more gradually from a BankAccount interface to a BankAccount class to a CheckingAccount subclass.

zokier2• 14 years ago

I haven't read the docs so I may be completely off. But that "super" syntax could be similar to "brace initialization" in C.

bmuon• 14 years ago

I don't think `super` can be invoked as a function yet. I think it's only a reference to the superclass' prototype.

camus2• 14 years ago

Funny how Microsoft refused ES4 because it came from Macromedia/Adobe ,yet now it pushes a language that looks like its own JScript/AS3

petegrif• 14 years ago

MS answer to DART?

arturadib• 14 years ago

All of these compile-to-JS efforts are great, and as much as I love things like CoffeeScript I have to say I definitely worry about language fragmentation.

JavaScript is full of flaws, but its monopoly in the browser space has brought about one intriguing and welcome side-effect: a VERY efficient market for both employers and employees.

It's easy to overlook how important this common denominator has been for everyone involved. Employees have a tremendous amount of mobility within the industry: don't like your current JavaScript job? No problem - just about every dot-com needs a JavaScripter. Similarly, companies can today tap into a tremendous pool of JavaScript developers.

In today's fast-paced development environment, the ability to hit the ground running is key, and I worry that fragmentation will introduce unnecessary friction in the industry.

latchkey• 14 years ago

This same fear of fragmentation is what kept Java from progressing for so many years and look what happened there. Things 'fragmented' by people just switching to other languages. I say roll the dice and see what happens.

camus2• 14 years ago

Javascript is dreadfull , and its flaws are counter productive and intolerable. It has good things like closures and first class functions , and that's it. Most of js developpers hate javascript , but are forced to work with it. So they dont care what they use as client language provided it gets the job done. few people cares about Javascript. most of the devs hate it. But the browser as dev plateform is a fact.

thedufer• 14 years ago

That is a sweeping condemnation of JavaScript that I've honestly never heard support for. JavaScript has quirks that people don't like, but it can be rather enjoyable to work with.

niggler• 14 years ago

I've only started playing with it recently, but I've been doing some heavy stuff and wonder whether the criticism stems from deficiencies in the language (for which there are workarounds within the language) or a fundamental lack of understanding of the javascript model.

jonknee2• 14 years ago

> Most of js developpers hate javascript

I don't know of any JS developers that hate JS. I know a lot that hate some browser implementations of JS though.

lowboy4• 14 years ago

Please don't speak for javascript developers without some substantiation of your opinions.

pacomerh2• 14 years ago

Nah, you're generalizing. I know many JS developers and they all love Javascript in one way or another.

jfoutz• 14 years ago

With a name like Camus, how can you not be a fan of javascript?

kofman2• 14 years ago

Agreed, it's a terrible language. Among other things, it makes it way too easy to write code which many people will read as being correct, but will actually be subtly incorrect.

A few of the weakest parts:

- for (var x in y) when used for array iteration or even dict iteration; hasOwnProperty? Really?

- x[obj] = y; seriously, did i really want '[Object object]' as my key?

- the choice of function level scope over block level scope

msteigerwalt• 14 years ago

From my experience, "most" of those JavaScript developers who "hate JavaScript" are in fact front-end developers who hate writing JavaScript for websites, since they struggle daily with issues such as cross-browser compatibility and inconsistent DOM implementations, which have nothing to do with JavaScript at all, and can't be fixed by a different syntax.

It's also compounded because the majority of front-end developers write their code procedurally for each application component, which creates a terrible nest of repetitive and error-prone code.

They feel the pain, don't know how to solve it, so switch to a different syntax, blaming that as the root cause of the problem.

But feeling enough pain to viscerally HATE a language, as many front-end developers do, is not something that can simply come from the syntax of the language and the fact that the equality operator does type conversion and whatever small list of gripes users have. Most other languages (including CoffeeScript!) have a similarly-sized set of flaws and aren't nearly as derided.

medikoo• 14 years ago

JavaScript is my main language since about 5 years, and I love it. I know a lot JavaScript developers and honestly I don't know any that "hate" the language, about 80% are very passionate about it, for rest is just tool to achieve the goals.

JavaScript has minor flaws but in general when understood it's outstanding. However it's not the style that you've been taught in school (OOP) and that's the problem for many newcomers.

It looks that you're just frustrated with something and want whole world to be as well, it won't work. Try CoffeeScript, it's much more approachable when coming from OOP world, then when you get how JavaScript works and understand it makes sense, you'll be ready to program in it directly.

georgemcbay5• 14 years ago

JavaScript is forever stuck in design-by-committee hell, which dooms it long-term. Developers who do nothing but pure JavaScript and don't at least play around with the other options (Dart, TypeScript, Haxe, CoffeeScript, et al) are just going to be hurting themselves long-term.

It is always a bad idea to tie yourself too strongly to any single language.

zachrose2• 14 years ago

I don't know, ECMAScript 6 looks a lot like Coffeescript, and ECMAScript 6 modules look a lot like Node modules.

edwinnathaniel2• 14 years ago

Conversely it's a bad idea to spread yourself thin in multiple languages but master of none.

Having said that, I'm pretty much tied to Java since 2000 and haven't seen anything wrong... yet. In fact, I'm determined to get better in Java everyday (memory model, JVM, concurrency, better design, etc).

Side note: I'm also learning pure "modern" JS just because there's no choice on the client-side.

eddieplan93• 14 years ago

I think you were referring to the JavaScript syntax when you said JavaScript is full of flaws, because IMHO the language itself - except the syntax component - is actually very good. Someone on Quora said[1] it very well:

JavaScript is a wonderful language, deep down: It's Lisp-y, yet imperative. Its lack of support for threads has turned out to be a strength on the server side. And recent implementations have made it very fast.

People favoring node.js and compile-to-JS languages like Iced CoffeeScript to other server-side languages supports the fact that JavaScript itself is actually quite decent. At the end of the day, a language too broken could not easily be fixed with any thin compile-to-* effort, and most of the compile-to-JS efforts (with the notable exception of emscripten, whose goal is not to fix JavaScript) are quite quite thin.

[1] http://www.quora.com/CoffeeScript/What-are-disadvantages-of-...

stdbrouw• 14 years ago

The intrinsic beauty of JavaScript doesn't matter in this context. Either you use JavaScript or you use something else, and if you use something else then that'll lead to language fragmentation, which is arturadib's concern.

norswap• 14 years ago

The good parts are good. The bad parts are pretty horrible.

zemo• 14 years ago

>Its lack of support for threads has turned out to be a strength on the server side.

ummmm, can someone elaborate? I don't understand that statement.

aaronblohowiak2• 14 years ago

The language itself is broken, especially when it comes to equality, type coercion, `arguments`, and Date processing.

zem3• 14 years ago

> In today's fast-paced development environment, the ability to hit the ground running is key

actually, i think one of the major flaws in the current programming job market is overrating the ability to hit the ground running. that leads to a dangerous level of short-term optimisation, where, say, you'd choose an employee who has experience with your current stack over someone with a better track record but requiring a month or so to learn their way around the specific languages and ecosystems involved.

libria• 14 years ago

It's good to see sharp developers like Anders Hejlsberg spearheading this. I really hope this means we'll get LINQ sometime in the future; good to hear generics are on the way.

devongovett• 14 years ago

My thoughts on Badass JS here: http://badassjs.com/post/32674515997/typescript-microsofts-n...

alexanderh2• 14 years ago

What about debugging? Thats my biggest problem with coffeescript

How do they map errors thrown in the browser, to TypeScript code? If this has things like classes and such, the relationship isnt always going to be 1:1 and debugging can become a nightmare. Part of what makes javascript so great is how easy it is to debug. All these "superset" languages that compile to javascript fail hard @ debug support usually

wingspan22• 14 years ago

Debugging would be helped greatly if they supported source maps (http://www.html5rocks.com/en/tutorials/developertools/source...).

munificent4• 14 years ago

Source maps[1] should help with this.

[1] http://www.html5rocks.com/en/tutorials/developertools/source...

alexanderh2• 14 years ago

This is cool and I keep hearing its coming to coffeescript soon, but just the fact that the TypeScript website doesnt mention "debugging" or "source maps" anywhere on the front page is disheartening. Its more important than anything to me, yet its still just a "we'll get there eventually" priority for all these alternative javascript languages.

I would think microsoft wouldnt want to release this until source maps were tested, working and included as part of the language as a major bullet point feature. These languages are nothing but a novelty to use in prototyping until that happens. I'll never use any of these languages in my production development workflow until proper debugging is available.

jrajav• 14 years ago

What's with the insta-downvotes whenever someone mentions Coffeescript's debugging issues? I am not an active Coffeescript developer, but I thought that debugging line-by-line was prohibitively difficult, especially in the browser. Has this changed? If not, why the animosity?

andrewla• 14 years ago

On a tangent, does anyone know anything about the in-browser editor they are using for the playground? It seems really slick. The javascript references something called "monaco" and the directories are all prefixed with "vs".

The code is hosted on their demo site; /Script/vs/editor/editor.main.js appears to be the main js file and has this notice:

    /*!
        © Microsoft. All rights reserved.

        This library is supported for use in Windows Store apps only.

        Build: 1.0.8514.0.win8_rtm.120711-1900
  
        Version: Microsoft.WinJS.1.0
    */

wingspan22• 14 years ago

I believe the monaco editor is already being used in Azure Websites and possibly the TFS preview. I wouldn't be surprised if more information about it would be released soon, they are also a major dogfooder of TypeScript.

jon62• 14 years ago

    $ t
    command not found

clearly they could have named the compiler just 't' instead of the overly verbose 'tsc'. all those extra characters!!

spicyj5• 14 years ago

The compilers for C# and F# are named csc and fsc, respectively. I think we can handle two extra characters. ;)

lowboy4• 14 years ago

If I develop an RSI and a doctor tells me it was by a matter of a hundred keystrokes, I'm coming for Ballmer's pelt.

ndabas• 14 years ago

    $ curl http://news.ycombinator.com/user?id=j
    No such user.

Clearly you could have named yourself just 'j' instead of the overly verbose 'jon6'. All those extra characters!!

jon62• 14 years ago

Clearly you can't perceive sarcasm.

eddieplan93• 14 years ago

This is quite impressive technically, and I think the type-checking feature alone can make it appeal to those making large-scale application in collaborative development environment. I hope this inspires other similar efforts. A quick run-down of features:

- It's a superset of JavaScript. So there is no porting effort needed. (With CoffeeScript, you do not need to port if you don't want to.)

- compile-time type checking, like type erasure in Java's generics.

- module support at the language level. It's very thin. It does not give your AMD or CommonJS module, but you can easily hack around it.

- class and inheritance support at the language level. The implementation is very similar to CoffeeScript's.

wingspan22• 14 years ago

With reference to AMD and CommonJS modules, the spec has more info [1]:

  TypeScript implements modules that are closely aligned with those proposed for
  ECMAScript 6 and supports code generation targeting CommonJS and AMD module systems.

It also looks like you can consume CommonJS and AMD modules using familiar constructs.

[1] http://go.microsoft.com/fwlink/?LinkId=267121

mbq• 14 years ago

Looks like all the bad features of Java and JS combined.

colin_jack7• 14 years ago

In case anyones interested, dart JS interop:

https://github.com/dart-lang/js-interop/

stalled• 14 years ago

(for posterity, stray duplicate discussion with exactly the same url: http://news.ycombinator.com/item?id=4597724)

iamleppert• 14 years ago

Why does everyone want to take all the nice features of javascript, it being so loose and freeform and turn it into Java? I don't need interfaces and classes built into the language. That's why it's so powerful and lightweight. Prototypical!

People keep making the same mistakes, if you let them.

No thanks.

winteriscomming• 14 years ago

Because these "loose and freeform" attributes make your life hell building large applications with large teams.

kami8845• 14 years ago

Because writing big apps in dynamic languages sucks (I say this writing primarily Python & JS)

tlrobinson3• 14 years ago

The static typing is optional. You can be all "loose and freeform" when hacking stuff out, and later add types in to solidify your code and check for errors.

It's the best of both worlds, IMHO.

SeanLuke• 14 years ago

> The scope of a parameter, local variable, or local function declared within a function declaration (including a constructor, member function, or member accessor declaration) or function expression is the body of that function declaration or function expression.

This thing claims to be meant for "application-scale" JavaScript, and yet doesn't repair even JavaScript's most notorious error?

A suggestion to the authors. Purchase this book:

http://www.amazon.com/JavaScript-Good-Parts-Douglas-Crockfor...

... then go through the book with a fine-tooth comb, and every time it describes something as a "bad part" or an "awful part", delete or fix that misfeature in TypeScript.

AdamTReineke• 14 years ago

Except then you would likely lose the attribute of being a superset of JavaScript.

clockwork_189• 14 years ago

Seems pretty cool, but how does it compare to DART or does it even compare?

aaronblohowiak2• 14 years ago

They added static typing to javascript, except you can still pass a number to a function that takes a string. In their example http://www.typescriptlang.org/Playground/ replace the

   new Greeter("World");

with

   new Greeter(5);

and it still works. What good is adding types to functions if they are ignored?

spicyj5• 14 years ago

In the "Walkthrough: Types" example (as well as the "Classes" one), that gives me an error.

glennsl• 14 years ago

TypeScript will not abort compilation, but it will give you a warning. In the playground, that would be the red squiggly line indicating an error.

ww520• 14 years ago

This looks very good enhancement on top of Javascript. Hope browsers start bundling the TypeScript compiler natively.

anuraj• 14 years ago

Wholeheartedly support this thinking softie has no daggers hidden. The changes do make the language more readable and maintaninable compared to the mess called JavaScript. If the IDE is support is also there, this will be a no-brainer.

nnq• 14 years ago

The only thing that I find "exciting" in the land of compiled-to-javascript languages is LiveScript (http://gkz.github.com/LiveScript/)...

oinksoft5• 14 years ago

It seems to me that the type checking in TypeScript is extremely limited compared to what the Closure Compiler supports. The examples only show simple `fooInstance : Foo` examples, whereas Closure supports function prototype validation and such, a la C. I will need to see more elaborate examples.

Granted, there is no documentation that I could find on the website. I understand that this is a "preview," but I disagree with this way of presenting a tool. When the Closure Library was released, for instance, it was absolutely chock full of API documentation. This is because it was used for real-world projects and extensive docs mattered, even internal to Google.

There is a language specification (PDF, in the source tree) which is encouraging, but where's the manual? <http://www.floopsy.com/post/32453280184/w-t-f-m-write-the-fr.... The specification is largely a rewording of the ES5 spec with insertions where the typing additions are important. It will take a good bit for the reader to separate the wheat from the chaff, as they say.

I have more than a sneaking suspicion that this project is essentially a proof-of-concept, and that it is not heavily used at Microsoft. Do you remember "Microsoft Atlas" in 2006, at the height of the JS DOM Library Wars? In the end, they just pushed their developers to use jQuery with some code generation helpers. Microsoft's open-source track record for JavaScript is not impressive, and I think you'd be a damned fool to invest in this technology for any serious project.

JimmaDaRustla2• 14 years ago

It's an open-source iniative - great ideas like this are best seeded and grown through a great community effort. You sound like you want to be given the whole tree.

oinksoft5• 14 years ago

I'll grant you that; I expect a more impressive release from a company like Microsoft. Why is there so much work put into the website when the tool and its documentation are sorely lacking?

wingspan22• 14 years ago

  I have more than a sneaking suspicion that this project is essentially a proof-of-concept, and that it is not heavily used at Microsoft.

My team has been dogfooding TypeScript for several months now, providing lots of feedback and writing > 30,000 lines of code (in many cases the new TypeScript code is shorter than the original Javascript).

oinksoft5• 14 years ago

In this case, I must infer that the culture of documentation is not the same at Microsoft as it is at Google.

Further, how can you have a tool like this and nothing for generating type-aware documentation from your source code? Google uses jsdoc-toolkit, so this is a moot point for them. Either you guys are using this in an informal fashion, or documentation isn't that important at Microsoft, or you just haven't released the doc generation tool(s), which would be a really odd choice!

rictic• 14 years ago

What's function prototype validation? Can you expand on this?

epidemian2• 14 years ago

It looks really good for a first release. The focus on tooling is IMO the most refreshing thing about the project; the playground is great!

I haven't dug much into it yet, but there are a couple of annoyances that i noticed in the playground that i wish will be corrected/alleviated somehow:

- The language is not expression-oriented. Once i got used to the "everything is an expression" mindset in languages like CoffeeScript or Ruby (or every functional language that i can think of) it feels quite tedious to "go back" and remember that, no, now the "if" is not an expression any more, you can't return it, or pass it to a function, or assign it to something. You can use the special syntax of the "?:" operator for an if-expression, but there is no equivalent for "switch", or "try", or "for".

- The type system doesn't seem to support parametric polymorphism. For example, the type of string[]::map is ((string, number, string[]) => any, any) => any[] instead of ((string, number, string[]) => T, any) => T[]. So the value ["hello", "world"].map((s) => s + '!') is of type any[] instead of string[], which would be preferable IMO.

wingspan22• 14 years ago

TypeScript will eventually support generics, as per the spec [1]:

  NOTE: TypeScript currently doesn’t support Generics, but we expect to include them in the
  final language. Since TypeScript’s static type system has no run-time manifestation, Generics
  will be based on “type erasure” and intended purely as a conduit for expressing parametric type
  relationships in interfaces, classes, and function signatures.

[1] http://go.microsoft.com/fwlink/?LinkId=267121

epidemian2• 14 years ago

Cool. It is quite expectable too, at least considering the capabilities of the C# type system :)

euroclydon4• 14 years ago

The compiler's written in... TypeScript!

euroclydon4• 14 years ago

What unit test framework are they using in the source? It looks like Jasmine ('describe', 'it') but then it has 'assert' and I can't find an include for it.

dotborg• 14 years ago

Reminds me about Turbo Pascal, I love it!

zoowar• 14 years ago

lol: application-scale

stuaxo• 14 years ago

Hm.. classes, interfaces... reminds me of AS3; which of course MS stopped becoming the next javascript.

Still - looks useful.

bilalq• 14 years ago

Am I the only one experiencing sluggish scrolling on that site? Rather ironic for a site boasting about application-scale development.

Zelphyr• 14 years ago

The Google guys called. They want Microsoft to stop being jealous of the JS-influenced turd that is Dart.

buremba• 14 years ago

I think javascript is awesome enough so it doesn't need any language improvements. The only improvement over javascript is coffeescript and it's just because its syntax nothing more else. take a look at this video from google i/o: http://goo.gl/BGvAS

FreshCode• 14 years ago

Could TypeScript be combined with the CoffeeScript syntax to save keystrokes?

malandrew2• 14 years ago

Like someone else commented in the TC article about Typescript, this Resig quote, changing "Google" for "Microsoft" is relevant:

  "Why is [Microsoft] putting time and effort into 
  changing JavaScript when the DOM is what needs fixing?"

https://twitter.com/jeresig/status/124114331616026624

munificent4• 14 years ago

Ironically, improving the DOM is actually something we're trying to do with Dart: http://www.dartlang.org/articles/improving-the-dom/.

malandrew2• 14 years ago

Those "improvements" really don't address what is wrong with the DOM. The problem with the DOM isn't that it could use a more consistent API with better interface naming.

The DOM simply is a poor abstraction for applications. For example, it doesn't have a concurrency model and many modifications to the styling of individual elements or changes to the DOM structure can cause repaints and reflows.

antidoh• 14 years ago

I wish they had named it something else. typescript is the default output file name for script(1).

http://www.unix.com/man-page/Linux/1/script/

DigitalSea• 14 years ago

I will admit MS have impressed me here. The fact they've released TypeScript under an Apache 2.0 licence and put the code up on CodePlex goes to show Microsoft are making strides in the open source community. A big change considering the mentality of MS used to be open source was unsafe and a threat to their dominance in the software industry. The world must be ending: Apple is starting to falter and Microsoft is climbing back to the top.

Floopsy• 14 years ago

(Wikipedia) “Some examples, like Dart, portend that JavaScript has fundamental flaws and to support these scenarios requires a ‘clean break’ from JavaScript in both syntax and runtime. We disagree with this point of view.” - Microsoft’s JavaScript team

If Google comes out with Dart, well, then there's no need for that. But it's ok for Microsoft to be secretly working on their own Javascript 2.0. Just sayin' - Why criticize Dart when you've just come with almost the same thing? :)

But snark aside, good job Microsoft. Well done.

josephcooney• 14 years ago

Treating Microsoft as a single, whole, coherent, consistent, and logical entity is the first mistake you make when trying to understand their actions and motivations.

BrendanEich5• 14 years ago

Also, no "JS will be replaced" threat, no proprietary native VM in IE-prototype to advantage it over other browsers running TypeScript compiled to JS.

But I agree it is another case of two-faced behavior, not in the way you suggest. The IE blog post against Dart rejects a "clean break" and TypeScript builds on ES6. That's consistent.

What is not consistent is how similar parts (but not all) of TypeScript are to ES4, which MS opposed vigorously. Time has passed and ES4 had its own problems, so bygones.

luke_s• 14 years ago

It seems the analyser to infer the types of your vars is fairly easily fooled. The following code compiles, but prints out "Hello undefined":

  interface person{
	firstname;
	lastname;
  }

  interface apple{
	colour;
  }

  function hello(p : person){
	alert("hello " + p.firstname);
  }

  var aPerson = {firstname: "joe", lastname : "blogs"};
  var anApple = {color: "red"};

  var foo;
  if(true){
	foo = anApple;
  }

  hello(foo);

wingspan22• 14 years ago

When you paste this into the Playground, and hover over the `var

ilaksh• 14 years ago

Not having to deal with types is one of the advantages of JavaScript. This actually makes it worse.

dreamdu5t• 14 years ago

The lack of strong typing in JavaScript is a feature not a bug.

pootch• 14 years ago

MS has no credibility in this space. If you think slapping an OSS license on their code gives them cred you must be some kind of fanboy. As for Javascript - well, browsers still sucks, webapps still suck, and web development still sucks. Javascript is a big part of that. 30%

charlieok• 14 years ago

So they've set up a site for TypeScript but as far as I can tell, that site hasn't got a blog. With so many projects vying for attention, subscribing to a project's blog is my default way of keeping it in mind for later. If they post interesting updates, I'll be reminded later to come back and give it a closer look.

dmorgan4• 14 years ago

Open Source? Node.js? Github? Javascript cross-compiler? ES6 based? Type annotations?

This is the first sign that they are "getting" 2012 developers and are back in the game with a vengeance. Hope it works.

Dart is mid-nineties MS by comparison.

dogada2• 14 years ago

One of the key TypeScript features is not only the fact that JavaScript program is TypeScript programs but also ability to add type annotations to existing javascript libraries without changing of their source code. For example, see port of Backbone's TodoMVC: http://typescript.codeplex.com/SourceControl/changeset/view/...

dogada2• 14 years ago

IMO Microsoft looks for web-developer loyalty because recent stupid policy of big monopoly drive them to zero share on web-browser market. The only remaining question: will IE10 support TypeScript or it will be added in IE11 only?

bbayer• 14 years ago

yet another language compiled to javascript. What is the deal with the adding type system without doing runtime checks? Does it solve DOM manipulation complexity or it just solve code readability problem? Does it worth to learn new language constructs when you decide to begin low or middle scale projects?

emillon• 14 years ago

Very good idea. But note that these annotations are just hints : they are enforced only in simple cases :

var x = "lol" - error found : http://pastebin.com/R1wqp0CS var x; x = "lol" - accepted : http://pastebin.com/0vc68RbY

Andi• 14 years ago

For stuff like this, you use schema.js.

TypeScript: a language for application-scale JavaScript development

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