With the threading issue, Web Workers are boxed up so tightly that there are a lot of operations, like passing objects between threads, or letting web workers have access to portions of the DOM, are impossible. Additionally, because everything's passed by value, there's a lot of copying that needs to take place; to expand on my prior example, sending a message to another thread would involve copying the object to send to the main thread, then copying it again to send to the destination thread. The alternative, transferrable objects, completely deletes the object being passed, and still can't be transferred between threads. Finally, there is no pooling control among threads, which means that there is a lot less control over what threads are running at any moment.
These problems all come back to the fundamental issue. There's no escape from javascript. Asm.js is fundamentally hung off of javascript with bailing wire and duct tape, out of fear of "breaking compatibility". Anyone that tries to experiment with a new language is immediately accused of trying to fracture the web. Thus, we stagnate, and everyone suffers for it.
It has all of these things. It has SIMD now, 64-bit support is improving, IEEE-754 is supported (though some of the checks aren't available yet, I'll give you that). Give it time.
> With the threading issue, Web Workers are boxed up so tightly that there are a lot of operations, like passing objects between threads, or letting web workers have access to portions of the DOM, are impossible. Additionally, because everything's passed by value, there's a lot of copying that needs to take place; to expand on my prior example, sending a message to another thread would involve copying the object to send to the main thread, then copying it again to send to the destination thread. The alternative, transferrable objects, completely deletes the object being passed, and still can't be transferred between threads. Finally, there is no pooling control among threads, which means that there is a lot less control over what threads are running at any moment.
Yes, but this stuff isn't applicable to asm.js. It shares a heap between threads, it's just like your old native code, and everything is triggering race conditions^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B^B hunky dory.
> These problems all come back to the fundamental issue. There's no escape from javascript.
What's wrong with that? If you don't like JS, you can compile to it. It's an excellent compile target.
> Asm.js is fundamentally hung off of javascript with bailing wire and duct tape, out of fear of "breaking compatibility".
It's not just a compatibility hack, though managing to work on everything with no updates is a killer and awesome feature. It also avoids unnecessarily reinventing the wheel. It reuses as much of JS as possible. That's good.
> Anyone that tries to experiment with a new language is immediately accused of trying to fracture the web.
...well, yes, they're fracturing it. And usually needlessly. There'd be no benefit to a new language on the web. There's nothing a new language can offer which JS doesn't have.
> Thus, we stagnate, and everyone suffers for it.
What stagnation? Everything is moving rapidly. Things are improving all the time.
I'd say that the weaknesses of web workers is absolutely relevant. Though you see it as protecting the coder from themselves, there are design patterns out there, like publish/subscribe, that are useful in letting threads communicate, but not generating race conditions. DOM access and the like can be done sanely, but Javascript doesn't even give you that option.
Given the reasons described, it's a rather poor compile target. It's a plodding beast of a language that mishandles numbers, requires circuitous coding to handle basic concurrency, and otherwise behaves in ways other languages don't. Transpiling just barely hides its flaws.
I will restate that it is a hack, and a rather ugly one. Its attempts to maintain compatibility leave us with a virtual machine that is increasingly obsolescent. An "assembly language" designed in 2013 shouldn't be lacking support for 64 bit integers (or 8-bit or 16), should have good support for vectorization, and should provide some sort of register and/or stack model so that you can better clue in the vm as to what items are going to be frequently used in functions. The missing features could be handled much like JSON was early in its life, by including a library as a fallback. It would probably end up looking ugly as hell, but at the same time, it would work, and give a lot more long-term benefits.
Regarding alternative languages, Javascript isn't always the best language to describe a problem in. Sometimes your program's better written in C, or Lisp, or Fortran even. Why should you force your problem to fit the language?
Regarding stagnation, you can move quickly, yet not really go anywhere useful. COBOL had 7 major versions and several minor in 14 years. Does it mean that it's a useful language today? The stagnation comes in terms of how people think of problems, and how they try to wedge those problems to fit into Javascript. The web would be a much better place if we allowed more experimentation into languages and behavior.
> asm.js doesn't support threading.
asm.js supports threading, actually, through Web Workers and SharedArrayBuffer.
> it can't run native code.
This is true, but asm.js is relatively close to the metal. It's not very far from assembly language.
> it doesn't support meaningful debugging.
This is a tooling issue. While the situation is bad at the moment, it'll surely improve.
> it doesn't have a post-DOM API surface like pepper.
Why do you need a "post-DOM API surface"? If you just want to blit stuff to the screen, the DOM is actually no less efficient than Pepper: you can directly pass it pixel buffers, or call OpenGL routines.