I think JavaScript will stick around for quite awhile. However, the viability and popularity of languages that compile to JavaScript will probably continue to increase.

Besides CoffeeScript, which mostly only offers syntactic improvements to JavaScript, there are several projects which compile very different languages to JS, including:

* Emscripten (http://emscripten.org/) compiles arbitrary LLVM bitcode to JavaScript. Since clang and GCC can both target LLVM, a whole lot can be compiled to JavaScript. The Python interpreter (http://syntensity.com/static/python.html) and the Bullet physics engine (http://www.syntensity.com/static/bullet.html) are both particularly impressive.

* Google Web Toolkit (http://code.google.com/webtoolkit/) compiles Java to JavaScript. It's used in many real projects. Scala+GWT (http://scalagwt.gogoego.com/) aims to use this toolchain to compile Scala code, though it's not yet production-ready.

* The reductio ad absurdum of this approach is http://bellard.org/jslinux/, a x86 PC emulator written in JavaScript. You can run almost any language in the web browser with that!

See https://github.com/jashkenas/coffee-script/wiki/List-of-lang... for a (possibly exhaustive) list of languages like this.

Whether these approaches can deliver passable performance for legacy browsers is an open question. However, for newer browsers it's safe to assume this general approach holds a lot of promise.

Google's Native Client [1] is one answer. It allows you to run native code safely in the browser. It's goal is also to support LLVM IL to run safely in the browser. This way you could potentially use all your favorite languages at nearly full speed, and also have access to the DOM and other browser APIs.

Another answer is to compile your favorite language down to Javascript. This gets you the expressiveness at the cost of a slowdown in runtime speed. Languages like Coffeescript are very close to Javascript so they don't incur much overhead by doing this, but even this approach can't go as fast as code running on Native Client.

[1] http://code.google.com/p/nativeclient/

While server-side JS such as Node.js might be a fad, client-side JS is firmly entrenched. Given the speed at which the browser developers and standards groups agree on implementing new standards (read: slow), client-side Javascript is here to stay.

However, CoffeeScript provides an interesting look into the future of Javascript. I also see a similar thing happening with CSS and Less, where people are no longer waiting for browsers to support features developers want.

And lastly, I personally really enjoy coding in Javascript. The ugliest part about it is the DOM and Jquery successfully hides that. I think part of the reason Node.js is so popular because of the strength and programmer joy of the language.

Mozilla is working on Rust https://github.com/graydon/rust/wiki/Language-FAQ. Google has Go http://golang.org/.

To run compiled binaries from such languages you'll use Native Client http://code.google.com/p/nativeclient/ and Pepper APIs which let you access HTML5.

Go gets rid of some insecure low level things like pointers, keeps such things in an unsafe package to discourage its use. They intend to make it seamlessly compatible with NaCl. C/C++ code needs to be modified to work there.

JS is already not suitable for lots of stuff. Vendors are stretching its capabilities with big teams of fancy programmers implementing fancy VMs with big chunks written in assembler. At Google I/O they mentioned V8 is about as fast as it will get. Then bigger teams are writing massive APIs because even with fast VMs the language isn't fast enough to roll your own CSS/XAML/MXML/HTML parsers or 2D rendering contexts. So you're forced to wait or hack together things like LESS, CoffeeScript, Stylus in an attempt to communicate with the overlords.

With the browsers becoming the operating system for many users, you need a runtime that's as powerful as a regular operating system. Google and Mozilla are major players and it's nice to see them exploring alternatives.

But even if NaCl/Go is superior technologically, it may not overcome JavaScript's business and political momentum. As usual, technology is not chosen based on technological merit, but business considerations like legacy, lock in, etc. Perhaps NaCl/Go approach will succeed but it will be too little too late. Kinda feels that way with Flash and Browsers, they're finally serious platforms but might be too far behind Objective-C, C# and Java on mobiles.

Well there's always been interesting talk about getting LLVM to run in browsers, which would be wicked cool, and open up a lot of different programming languages.

That said, JavaScript really is an awesome language to use, if you can get over the syntax. So i really can't see how JS would be unsuitable for future use, especially in light of the changes that have happened and continue to come down the pipeline in newer versions of JS.

Coffeescript is a fantastic view of the power and capabilities of JavaScript packaged in a way that is considerably more elegant to look at and use on a daily basis. Check out the talk that Brendan Eich and Jeremy Ashkenas did at JSConf (http://news.ycombinator.com/item?id=2662846 ).

Javascript really is going to be a development powerhouse for the foreseeable future. And i'm actually happy about that.

No one language can meet every need. Even if it has been done, Javascript is a terrible language to write an MP3 decoder in, relative to more suitable languages. So if we're continuing to expand what the browser can do, shouldn't we expand what languages we can express them in? Why do we have to write our WebGL programs in Javascript? Javascript isn't a terribly great bytecode language, either, unless you're basically just writing a thin skin over Javascript.

The logical conclusion of this line of argument is pretty much NaCL: http://code.google.com/p/nativeclient/ Is that the anwser? Is there some intermediate where Javascript isn't the only choice for everything but we don't go to the other extreme?

Beats me, but we'll all find out together. But my main point is that it definitely is not the case that Javascript is just the answer to everything and the situation is just peachy keen as it is. It isn't the answer to everything. No one language is. Either we get something else into the client, or we face some combination of wasted effort jamming programs into a language that doesn't really want them and applications simply never written because they don't work well with Javascript's abstractions. Maybe that's OK too, maybe we want a distinction between "native" and "web" app.

So i'm curious what you mean by "more suitable languages" for writing an mp3 decoder. Also which of Javascript's abstractions are do you think are so inherently unsuitable?

As far as general purpose programming languages Javscript does pretty well with regard to object semantics. That's why things like Coffeescript are as powerful as they are. Javascript certainly doesn't have the elegance that say Ruby or Python has built in, but thanks to JavaScript's powerful and flexible nature, a lot of those capabilities are possible to build on top of JS's core.

http://documentcloud.github.com/underscore/ (which was also written by jashkenas and others) is a great example of this.

On the performance front, given all of the work that's gone into the various browser implementations of JS, that you could call it unsuitable from a performance standpoint. Could perhaps elaborate on this further?

"Also which of Javascript's abstractions are do you think are so inherently unsuitable?"

No, that's the wrong way of thinking about it entirely.

When you create a language, you must unavoidably privilege some ways of thinking and working above others. You must make some things easier, at the expense of making some things harder. There's no one set of answers that works universally.

Suppose I want to make an immutable language. Can I program Javascript purely immutably? Well... sort of. You can try, anyhow, but you'll get no help from the compiler, and any existing libraries will be all but useless, it's really a new language. Suppose I want to prove things in Javascript; with both mutable values and object prototypes that can be freely rewritten at any time, it's infeasible. Suppose I need C++; where's my private variables? Expressable? Sure. Useful? No; Javascript has made them much harder while working on making its object system powerful in different ways. That's not a criticism; a language has to make some things harder when it makes some things easier, to be a criticism I'd have to be calling it a "bad tradeoff", which in most cases it isn't.

It's not whether a thing can be done, it's how well it can be done, and Javascript isn't the best at everything. And "how well" something can be done matters, because the harder you make it, the less likely someone is to do it. No amount of theorizing how that doesn't have to be the case will change that.

There's nothing that any Turing Complete language can't do (with the proper hooks into the machine it's running on, anyhow), but no one language can be the best choice for everything. I wouldn't want to try to make an OS out of Javascript. Now, I personally wouldn't want to try to make one out of C particularly either, but Javascript would be even worse.

So either we lock all those apps out of the browser, or we make them much harder to write than they would be in a language actually suited to them. There's a time for C and a time for assembler and a time for Haskell and a time for C# etc. etc. Languages profoundly affect what gets written in them.

The two things i have to say in reply to that. First, i think there's a lot of bunk common wisdom about tradeoffs as well. Scala's a great example of a coherent merger of object oriented programming and functional program, two paradigms that have for whatever reason been typically seen as oppositional (please note, i'm not accusing you of that, but i think it's reasonable to ask which things you think are unsuitable, understanding that there are tradeoffs). Second, when you're talking about suitability, i have to ask about what your constraints are. If all languages have their tradeoffs, then i don't see the problem with saying that JavaScript is as good a general purpose programming language as any other. Sure it's got tradeoffs, but JS as a language and as a programming platform has really hit a firm stride, and clearly has at least a couple years of solid growth ahead of it. Yes, JS like any other programming language, isn't perfect, but it is going to continue getting better and growing into new niches.

An example that shows that Javascript wasn't designed for performance: it doesn't support integers. They can be used in some Javascript implementations that do smart tricks to convert float arithmetic to integer arithmetic, but it is not reliable. If you were designing a language for performance in the first place, this would be a ridiculous method to get access to integers. Same for dense arrays. Yeah, JS is pretty fast if you know how the particular implementation that you're targeting works, but even then there are many things that just need a lot more performance than JS can offer.

On the expressiveness front: Javascript doesn't support proper lexical scoping. It's object model is broken. It doesn't use proper abstractions in the standard library. Etc. These can all be fixed by compiling another language to Javascript, but then you lose on the performance side.

Dense arrays are coming in Harmony, thanks to WebGL. (JS.next)

CoffeeScript incurs no penalty when compiling to Javascript; in fact, in many cases it's faster than handwritten code.

CoffeeScript is only kinda "another language." It's very intentionally designed to map closely to JavaScript. Try it with an actual independent language like Python, Ruby or Haskell and you'll have more trouble.

Yea, Coffeescript incurs no penalty because it's so close to Javascript, but therefore it doesn't fix Javascript's flaws either. Coffeescript still doesn't have proper lexical scoping and it doesn't have a good standard library.

It sure fixes a lot of the expressiveness problem.

Nitpick: "Lingua franca", not "lingua de franca"

http://en.wikipedia.org/wiki/Lingua_franca

Also: no, probably not. We're still dealing with browsers that are 10 years old, so even if you were to release a browser, with, say, Tcl as the default language, it'd be years before it was something you could count on being everywhere.

See: positive network externalities, and "lock in".

I'd like to see a statically typed language available. There is relatively little I do that requires dynamic typing, but so much of my experience would be better with static typing.

I'm not saying to get rid of JS, but it would be nice to have a first class alternative.

JS is adding limited static typing in typed arrays: https://developer.mozilla.org/en/javascript_typed_arrays

Nothing about Typed Arrays is static typing.

Thanks. I thought I was the only one with this experience.

Some effort is being made to bring other languages to the web. Emscripten is a backend for LLVM to produce javascript code (should work with any LLVM frontend). NACL (native client) is a project by google to allow code to be compile for a more secure subset of x86 and to run on a browser safely. I'm not sure on the stability or use of either. GWT (google web toolkit) is a project that compiles java to javascript. This one should be fairly stable and seems to be well supported.

What, specifically, would you like to see changed?

It is evolving: Coffeescript, node, npm, and V8 are four examples. It can feel good to code in JS, just like it can in Python or Ruby (or Scheme :-) ).

No? It's only important because everyone has a javascript interpreter. The point will become moot as Javascript interpreters get good enough to allow us to run with languages that compile down to Javascript and enable more optimizations like typed arrays.

While I realize that Flash is no longer in vogue these days, ActionScript 3 is a really nice language and I'm surprised nobody else has mentioned it. It provides things like optional static typing for speed improvements, code clarity, and improved tooling/refactoring, as well as classes and packages for organizing larger code bases. It's more of what Brendan Eich envisioned JavaScript 2 to be.

That said, Apple is making it really hard for developers to choose it for all but intranet apps (for which it's really well suited).

I second GWT and the responses here have prompted me to look into CoffeeScript, so thanks for asking this!

The number of new features added to JavaScript in the past year is substantial. Between Canvas, WebGL, WebSockets, WebWorkers, Audio Data, TouchEvents, the number of permutations of new kinds of browser-based apps you can build will keep anyone busy for years. Then add NodeJS, and CouchDB, and the use of JSON as a data interchange and there are things you can do entirely in JavaScript that no other language can do.

If JavaScript continues to be improved (Harmony, V8/Spidermonkey engines, etc) then I see no other language on the horizon that will replace it.

Everything you listed actually has nothing to do with Javascript as a language. These are new frameworks for the and clientside APIs, not language features.

That's like saying the addition of the DOM did not improve Javascript. Standardized API's do matter, and do improve programming languages.

Frankly I really like JavaScript. I don't want the language to change, even though it has its flaws. I just love the ability to have data-structures as simple as objects and arrays which have evolved into a standard data exchange format (JSON). Then you can also have functions inside objects and everything becomes really flexible and really easy to design.

I've tried many different languages, including the real pretty ones such as Ruby and Python, and I just have more fun using JavaScript because of how free-form it is.

That flexibility is indeed useful for scripts and adding minor interactivity to an otherwise static web page.

However, people are now using JavaScript for development that far exceeds those uses. JavaScript is just not suitable for larger applications.

Once your application starts exceeding a few thousands of lines of code, the problems become very clear. You soon wish you were using a language like C++, Java, C#, Python, or Ruby. Toss in a development team made up of at least several people, if not more, and the pain becomes far greater.

I was never able to personally judge that statement. My experiences show that the flexibility of JavaScript only improved maintainability of the software written in it.

http://npmjs.org/ is a list of solid software (also large software) written in JavaScript.

So I don't think your statement, about maintainability being connected with how flexible a language is, can be proven to be true.

By "larger applications", I wasn't talking about jQuery, Node.js or anything built upon them.

I'm talking about real software systems with, at a very minimum, tens of thousands of lines of code. More realistically, we're talking systems with hundreds of thousands, if not several million, lines of code.

C++ can scale up to codebases that large. Java and C# can handle it, as well. Even Python and Ruby can, if care is taken. JavaScript cannot. You'll be hitting numerous maintenance barriers far before then, when you're still well under 10,000 lines of code.

Why do you think JavaScript cannot handle it? If you reach the million lines of code you probably have a really modular application, otherwise it's unmaintainable in any language. Being modular it can be sub-divided in many small layers which are the size of a jQuery library.

I think your experience with JavaScript comes from reading code made by bad developers. If your software is written by good people it will be maintainable even in JavaScript.

I've worked on some larger applications in javascript (though nothing incredibly large), and I can tell you if I had the choice of using any language that offered static and strong typing I'd take it in a heart beat. A small change in one place often means an error in some part of your code you didn't even think would be affected. I've loaded 65k LOC JS files in firebug and webkit's debugger chasing some error down that was happening in some piece of code that I've never seen before. All because that's how far my screw up managed to travel when there is no type checking or strong typing. In that particular case I had set a string value to something that was supposed to have been an array. Something like that would never have happen in, lets say C#, but "crap"[0] or "crap".indexOf("c") or ["c", "r"].indexOf("c") are all valid JS.

Dynamically typed languages offer a lot of benefits and a lot of burdens. Only you can judge whether you're willing to take those risks. Personally I am more comfortable with dynamically typed languages as they feel more natural and less programmatic, but this is just personal taste.

Nothing of this is related to the free-formness of JavaScript. Python and Ruby are also dynamically typed.

I have no experience with ruby, but python's advantage is in strong typing. Try and add an int and a string and you'll get a type error, JavaScript on the other hand will do it though. While maybe allowing you to write more expressive code, it does mean that errors become harder to locate, and when dealing with larger applications, I prefer being able to locate errors quickly.

coffeescript - it's just javascript, but with a touch of awesomeness.

And without proper stack traces.

Don't get me wrong, I love coffescript, but it clearly is a hack.

The internet landscape would look very different if browsers had a standardized bytecode interpreter.

Not just a hack. Recognized developers such as Brendan Eich (creator of javascript) or Douglas Crockford (author of Javascript: The Good Parts) say that Coffeescript is good stuff. Coffeescript is a "transpiler", a source-to-source compiler wich translates a high level, very flexible and powerfull language such as coffeescript into plain old javascript. It doesn't change the underlying language at all, it keeps its object model and its data types. It just adds a more expressive and succinct syntax, inspired in python and ruby (and these languages have a very well deserved reputation for expressiveness and joy amongst programmers for a reason).

Source-level stack traces are coming, to Firefox first. I would imagine WebKit will follow. IE perhaps not, but, personally, I intend to ignore IE in future web apps, until it mostly catches up with the front runners.

I don't think that the problem is that javascript is bad, but that it will kill most other scripting languages just by being in the right place at the right time.

It will be harder and harder for ruby/python/perl/x to compete with js in the future just because people know js and because it essentially runs everywhere fast.

WebCL, WebGL and friends will cover anything with extreme computational needs, and that will be everything you need to learn to write applications in the future, unfortunatly.

I think the execution of native code from the browser is slowly creeping in, in such a way that you'll be free to choose your language as you are in non-browser areas. Google native client, webGL and the ultra-new webCL are glimpses into the future. Javascript has served us well, but if we can avoid unnecessary computation as well as make use of existing code bases, then I am sure we will, eventually.

What do you think it might turn out to be unsuitable for?

Just like some languages have tools to translate them to C, there's no reason why you wouldn't use a tool to compile from a language more appropriate to your task, into javascript.

Why is JS not "reliable"? Any language can be a JS alternative. Do you mean you want an alternative language that runs natively in browsers?

"alternative language that runs natively in browsers"

That's already been done: http://code.google.com/chrome/nativeclient/

That doesn't run in browsers, it runs in one browser — Chrome.

Check out http://runrev.com/

I believe the most popular website is essentially an interface for this collection of hyperlinked documents. Document browsing is still one of the killer features of web.

HTML is not a bad layout engine for GUI apps. It may not have been initially been designed as one, but after 15 years of development it seems to be pretty pleasant to work with as there are people who want to build their desktop apps with HTML.

Obviously, the standard request-response model of HTTP is limiting for interactive apps. Bi-directional communication within request isn't possible and handshaking is a bit too expensive. But hey, this problem is actually solved: http://dev.w3.org/html5/websockets/.

JavaScript will be superseded by, what else, C/C++. Right now there are no JavaScript killer applications on the web. Adobe and Microsoft tried with their respective wares, but Apple interceded and stopped both.

It's hard to imagine now, but something will come along that, like web services, finds a slick way to give the folks what they want, performance.

And that innovation will be written in C.