Comment by edtechdev | Hacker News Reader

Comment by edtechdev | Hacker News Reader

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It's still a bit surprising that types were never (and still haven't been) added to javascript, as proposed for javascript 2.0 back in 1999: http://web.archive.org/web/20000817085058/http://www.mozilla...

Now we have Google's Dart & Closure compilers, Microsoft's TypeScript, and Mozilla's asm, all of which essentially add types back to javascript, not to mention about two dozen other statically typed javascript compilers: https://github.com/jashkenas/coffee-script/wiki/List-of-lang...

If types were approved 13 years ago, javascript apps could have been made to run much faster (fast enough for games even), perhaps negating a need for 'native' mobile apps that we have today, and either hastening the demise or spurring the optimization of competitors like Flash and Java and .NET/Silverlight.

(I'm already aware of arguments against static typing, and against having a VM in the browser or treating javascript like one.)

It's a lot harder to add types to a general purpose programming language. Your types have to match actual programming idioms, and if you care about them being safe (which, to be fair, recent languages like Dart and TypeScript don't), you have to consider every possible loophole that could lead to a dynamic error -- and the legacy language fights you, because all of its dynamism was designed back when nobody was thinking about respecting some not-yet-existent type system.

The type system for asm.js is a far more restricted problem, which is why we were able to come up with a solution so quickly (we only started this project in late 2012). The type hierarchy is extremely spartan, and it's just designed to map a low-level language (intended for compilers to be writing in) to the low-level machine model of modern computers.

Adding a static type system to JavaScript would have, IMO, been a losing effort. You can take a look at ActionScript 3 for an example of the challenges that come up.

Once you've got a static type system, you need a GOOD static type system, and imposing one of those on JS without breaking backwards compatibility would have been an ordeal and complicated code tremendously.

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