* Javascript has some warts, and here are some examples.
* It's going to take way too long to get these fixed to the point that we can actually start using new versions of Javascript because of slow browser adoption.
* To get around this problem, people are treating Javascript as a compilation target for other languages, the most prominent example being CoffeeScript.
* Discussion follows of features that would make Javascript better serve its increasing role as a compilation target.
* There is discussion of Harmony throughout.
Sometimes offering a TLDR indicates that the article isn't worth reading "so here are the author's points so you can skip it". That's not the case here. For example, I learned about "Tennet's Correspondence Principle", which helps to give a name to the different ways procs/blocks and methods/lambdas behave in Ruby, as explained in this article[1].
What if the standard could be changed from a language to a runtime specification? For example, a subset of LLVM assembler could play the role of a substrate (very much like what NaCl is doing) and leave the language part open. Runtimes with sufficiently rich capabilities can evolve over a much longer period than languages. This could liberate client-side coding from language specific-ness just like it doesn't matter what language you use on the server side.
That might sound a lot like Java, but it can can use some fresh thinking. I'm quite excited about NaCl on this front, for example.
"It's going to take way too long to get these fixed to the point that we can actually start using new versions of Javascript because of slow browser adoption."
Which isn't true, because you could compile newer versions of javascript to older versions. I see languages like coffeescript as interesting experiments in how the language can evolve, but eventually it needs to come back home to javascript and get deployed natively in browsers.
> If your application uses the let idiom, wouldn’t it be nice to have new syntax for it?
Mozilla introduced this back in Firefox 2, and you can replace var with it, so TFAA's
for (var i=0, ilen=elements.length; i<ilen; i++) {
var element = elements[i];
let (num = i) {
LIB_addEventListener(element, function(event) {
alert('I was originally number ' + num);
});
};
}
becomes:
for (let i=0, ilen=elements.length; i<ilen; i++) {
let element = elements[i];
LIB_addEventListener(element, function(event) {
alert('I was originally number ' + i);
});
}
Of course, since this does not quite seem to be a tight loop you should be using Array.prototype.forEach instead:
elements.forEach(function (element, i) {
LIB_addEventListener(element, function(event) {
alert('I was originally number ' + i);
});
});
> The JavaScript idiom that potentially spans the most lines of your program may be the inheritance idiom.
That's not an idiom. And there are numerous implementations of classes on top of prototypes out there, if there's one javascript "problem" which does not need new syntax it's that one.
Your example shows how the author's conclusions are wrong. IMHO the biggest milestones of Javascript life have been his libraries and the creative uses we have seen around them. From XMLHttpRequest to jQuery (and Prototype, Mootools, etc) and now Node.JS there have been highly disruptive innovations over this basically flawed language.
Maybe we should give more attention to the basic process behind this, creating libraries aka Programming Motherfucker.
Actually, the forEach version can end up faster than the let version... especially if you self-host forEach so that the JIT can do its job (e.g. inlining the LIB_addEventListener calls so there aren't actually any function invocations, etc).
Since JavaScript will still invoke a function call even if the number of arguments don't match up, parameter defaults will not completely eliminate all the problems he lists.
function(a = 1, b = "Smith", option = {}) { .. }
Will still break upon trying to invoke it without parameter 'b' since param 'option' will just take its place while option will become an empty object.
Furthermore he argues against "option = option || {};" only to do the same thing in the function header: "function(a, b, option = {}) { .. }"? What difference does that make?
The whole section in my opinion is negated by passing object literals to functions. Stuff like:
func({ a: 1, b: "Smith", option: { .. });
That makes it easy to read and easier to handle since names are agreed upon by both the caller and the function handling the invocation:
var opt = config.option || {};
This is a common practice in JavaScript already, and it beats the solutions he wished were added to the language.
I'm very much in agreement with objects-as-named-params. Default params just mitigate the problem, ambiguous function calling still rears its head as soon as you have multiple optional arguments of the same type.
As to the "option = option || {}", he was referring to the ultimate "option = {}" assignment if you passed a falsy value (0, "", false), which is different than if you didn't pass a value (undefined). Which is resolved by "option = option === undefined ? option : {}", which is even larger and kinda ugly.
His point is that if config.option is supposed to be an integer, not an object, then your proposed syntax falls down when trying to determine whether 0 was passed or whether nothing was passed.
"Do you want to maintain a compiler? Does anyone on your team have the skills to do that? That ulcer is going to get pretty big while you prepare to explain to the CEO that you now need to rewrite the UI in JavaScript."
GWT could be really strong. But it's this single maintainer problem that I think prevents it's penetration into the market.
Sadly when I hear people talk about the "strengths" of GWT, debugging and IDE debuggers is what I hear most. If that is the core reason for using GWT it seems shortsighted.
And for me personally I find that using Java (static typed system) to compile down to JavaScript (dynamic function system) is too big a paradigm switch for developers to maintain. Other languages, specifically functional type languages are far better for maintaining language paradigms in compiler situations.
Why isn't the 'single maintainer problem' a concern with other programming languages? What language DOESN'T have a single organization leading its development? Even worse, some projects (incl. coffeescript) seem to be controlled by just a handful of individuals who can easily be hit by a bus, hired away to do something else, lose interest, etc.
I think the only way to defend against that is to have an open source project, and to have a sufficiently large user base such that someone is sure to take over if the owners drop the project.
I think the strength of GWT is that for some languages/teams, a statically typed language is more appropriate than a dynamic language. And isn't more choice a good thing? Avoid the whole 'this is a hammer, everything else is a nail' approach?
I do agree that some teams choose GWT for inappropriate reasons though.
So... what you're saying is that having better tooling is a bad thing?
Disclaimer: I've done GWT and I liked it.
I did not find any Java<->Javascript paradigm shift problem at all. You simply forget about the Javascript and just write Java.
The big benefit of using GWT over writing 'native' javascript is that you get the same behaviour on all browsers.
The big benefit of using GWT over using other java based web frameworks is that GWT moves the client's state down to the client, where it belongs.
If you look at most other Java web frameworks like that (e.g. Struts and it's direct competitors), they expend enormous effort porting data to and from the client, and trying to hack around the limitations of the HTML post operation - namely that blank values aren't returned (checkboxes!!) and that everything is passed as text (numbers!!). So what these other frameworks do is they end up making you write all these model objects, and then try to simulate the client state. JSF is the worst of these as it takes it the furthest, they're not just emulating the model, but also the view as well with their overly-complex de-hydration and re-hydration of components.
If you tell the client state to bugger off back to the client where it belongs, you save a good 30-40% of your typical web framework effort right there.
Eliminating Javascript browser/version idiosyncrasies saves you another 20-30% of your effort (more if the UI is very dynamic, less if it isn't).
-----
I think you're posting on the basis of assumptions you've made based on what you've heard about GWT, rather than experience with it.
He calls inheritance in Javascript a wart. It's one of its major strengths, IMO: the fact that you can directly override methods for a single object. Class inheritance, as he'd like to see, is not all it's cracked up to be. Just look at Java with its anonymous inner classes, for one incredibly ugly construct...
BTW an easy way to produce traditional class inheritance in Javascript is to have a single instance from the class you're trying to inherit from, as the prototype. (To work properly that object should be "abstract": have no ties to any physical resources, like a browser widget, a database handle or a file handle.)
> Class inheritance, as he'd like to see, is not all it's cracked up to be. Just look at Java with its anonymous inner classes, for one incredibly ugly construct...
I'm not sure why you're implying java's anonymous inner classes have much relation with class inheritance.
The vast majority of class-based languages do not have (or need) anonymous inner classes (though some languages allow for creating unnamed classes on the fly by instantiating metaclasses).
Plus, I tend to prefer prototypal inheritance to classical inheritance. I do agree that the constructor pattern using the new keyword and the prototype object is a bit odd, but that's not the only way to have objects inherit from other objects in javascript.
He did mention the GWT Java to Javascript compiler. I have been using GWT (actually SmartGWT) a lot lately because one of my customers uses it. Except for long build times, the GWT Java to Javascript compiler has a lot going for it. Once a project is built and running in test + debugger mode, the client side development experience is pretty good.
Why not just have a library in Javascript, for example:
Q.each(arr, function(i) {
this.rocks();
arr.pop(); // watch out doing this in the loop
arr.push('foo'); // watch out doing this in the loop
});
Q.each(obj, function(k) {
this.rocks();
delete obj[k]; // should be safe maybe
});
var p = Q.pipe(crazy stuff involving pipes and callbacks)
doSql("SELECT * FROM users", p.fill('users'));
getUsers = Q.getter(getUsers); // turns it into a really smart getter
getUsers = Q.batch(getUsers); // turns into into a batched getter
and lots of other stuff
Why must the language take care of everything for you when libraries can do it? That has been the case with C, C++ and other languages.
Features that can be added through libraries should be added that way. You cannot add new syntax which involves scoping of variables through libraries. How would you do destructuring assignments with a library and have it as succinct as it can be done with syntax?
I tend to agree that compiling to JavaScript is the future of browser programming. CoffeeScript seems to be a nice language, but I bet there will be many more to come in the next year or two.
I hope someone writes a decompiler for one of these supra-JS languages (not sure if CoffeeScript is Turing-complete) to run against existing Javascript codebases. It could well speed up adoption if a mass-tangle of JS can be boiled down to a more readable and understandable structure.
What happened to the idea of standardising Mono (the open source .NET) bytecode as a new browser language?
Then you can use whatever java-like/basic-like/functional-like language you want, and have it compile to bytecode. Also, with sophisticated JITs for that style of bytecode already lying around, you could probably instantly beat javascript's performance even under the best engines, because of static typing etc. rather than relying on ridiculously complicated static analysis.
It'd have to be supported side-by-side with javascript for the forseeable future, but the earlier you get a change like this in, the better...
1. JavaScript's speed is actually not far from Mono's now. And constantly getting closer.
2. I don't think anyone but Microsoft would support .NET bytecode in the browser, simply because Microsoft controls .NET and has patents on it. It would take a lot more to reassure other browser vendors than Microsoft's existing CPs.
3. Running dynamic languages on Mono is slow. Look at the speed of all the dynamic languages on Mono (or the JVM for that matter), and compare them to native implementations of dynamic languages, in particular JavaScript and Lua. The native implementations beat dynamic languages on Mono by a large margin, simply because .NET is a bytecode made for static languages. Of course you can say that you prefer to have static languages in the browser over dynamic ones, that's a legitimate opinion of course, but not everyone would agree.
4. Standardizing on bytecode can inhibit innovation. JavaScript doesn't have a bytecode standard, which let JS engines implement very different ways of running it (V8 doesn't have a bytecode interpreter at all, for example). Of course standardizing on syntax also inhibits innovation, just in other ways, it isn't clear which is better.
5. Static languages compiled to JavaScript (that is, that use JavaScript as their 'assembly') are getting quite fast. Some benchmarks I ran found them to be around 5X slower (on the development versions of SpiderMonkey and V8) than gcc -O3, compared to Mono which is 2.5X slower, http://syntensity.blogspot.com/2011/06/emscripten-13.html
6. There is already Silverlight/Moonlight which does .NET in browsers, and it hasn't been very successful. (Of course it is a chicken and egg thing, if it were bundled in browsers it might be more popular. But the failure of Silverlight is a disincentive to add Mono to browsers nonetheless.)
For all these reasons, I don't think Mono has much of a chance to be included in browsers. Most of the same arguments apply to other static-language bytecodes like NaCl.
"In 1997, I collected a list of languages with compilers to JavaScript. There were JavaScript extension languages: the now-defunct ECMAScript 4, Narrative JavaScript, and Objective-J. There were pre-existing languages: Scheme, Common Lisp, Smalltalk, Ruby, Python, Java, C#, Haskell, etc. There were even brand new languages HaXe, Milescript, Links, Flapjax that were designed to address web programming needs."
Am I reading this right? Objective-J (2008), C# (2001), HaXe (2005), etc having compilers to javascript in 1997?
I like the prediction, but I think the biggest hurdle to compiled javascript will be mobile browser usage. The javascript interpreters in the mobile browsers right now are dog slow compared to their desktop cousins.
Android 2.2 and later uses Google's V8 JIT. iOS 4.3 and later uses Apple's Nitro JIT. Firefox 4 and Opera 11 also have JIT compilers enabled for ARM devices.
Mobile processors are still slower than desktop ones, of course, but JavaScript on mobile today is already faster than JavaScript on desktop just a few years ago. For example, the benchmarks on http://arewefastyet.com/ show V8 running only about 5x slower on an nVidia Tegra 250 ARM board than it does on an Intel Core 2 Duo Mac Mini.
I really hate when "X is dead; long live X!" is misused like this. The original phrase is "The king is dead; long live the king!", used when the OLD king died and the NEW king takes over.
Googling around, I see tons of misuse:
Example of bad usage: "White Stripes are dead (long live white stripes)"
Example of proper usage: "Palm is dead; long live Palm!" (this would mean that Palm got acquired or reformed)
"Paper is dead; long live paper!" (could be proper if used in an article about how paper for PRINTING is dead but paper lives on in other forms)
They didn't say "The King Henry VIII is dead. Long live the King Edward VI". In the JavaScript article, The "OLD king" is "JavaScript the source language". The "NEW king" is "JavaScript the compilation target". So the idea of old and new is in there. Sort of. :-)
Improvements to javascript would be great, but none are actually needed, the language is quite functional as is. Learn how to code or use coffeescript or develop your own new language to compile into javascript to support whatever language crutches you need.
[+] [-] kbd|14 years ago|reply
* Javascript has some warts, and here are some examples.
* It's going to take way too long to get these fixed to the point that we can actually start using new versions of Javascript because of slow browser adoption.
* To get around this problem, people are treating Javascript as a compilation target for other languages, the most prominent example being CoffeeScript.
* Discussion follows of features that would make Javascript better serve its increasing role as a compilation target.
* There is discussion of Harmony throughout.
Sometimes offering a TLDR indicates that the article isn't worth reading "so here are the author's points so you can skip it". That's not the case here. For example, I learned about "Tennet's Correspondence Principle", which helps to give a name to the different ways procs/blocks and methods/lambdas behave in Ruby, as explained in this article[1].
[1] http://www.robertsosinski.com/2008/12/21/understanding-ruby-...
[+] [-] aufreak3|14 years ago|reply
That might sound a lot like Java, but it can can use some fresh thinking. I'm quite excited about NaCl on this front, for example.
[+] [-] Joeri|14 years ago|reply
Which isn't true, because you could compile newer versions of javascript to older versions. I see languages like coffeescript as interesting experiments in how the language can evolve, but eventually it needs to come back home to javascript and get deployed natively in browsers.
[+] [-] masklinn|14 years ago|reply
Mozilla introduced this back in Firefox 2, and you can replace var with it, so TFAA's
becomes: Of course, since this does not quite seem to be a tight loop you should be using Array.prototype.forEach instead: > The JavaScript idiom that potentially spans the most lines of your program may be the inheritance idiom.That's not an idiom. And there are numerous implementations of classes on top of prototypes out there, if there's one javascript "problem" which does not need new syntax it's that one.
[+] [-] jacabado|14 years ago|reply
Maybe we should give more attention to the basic process behind this, creating libraries aka Programming Motherfucker.
[+] [-] bzbarsky|14 years ago|reply
[+] [-] nxn|14 years ago|reply
Since JavaScript will still invoke a function call even if the number of arguments don't match up, parameter defaults will not completely eliminate all the problems he lists.
Will still break upon trying to invoke it without parameter 'b' since param 'option' will just take its place while option will become an empty object.Furthermore he argues against "option = option || {};" only to do the same thing in the function header: "function(a, b, option = {}) { .. }"? What difference does that make?
The whole section in my opinion is negated by passing object literals to functions. Stuff like:
That makes it easy to read and easier to handle since names are agreed upon by both the caller and the function handling the invocation: This is a common practice in JavaScript already, and it beats the solutions he wished were added to the language.[+] [-] Groxx|14 years ago|reply
As to the "option = option || {}", he was referring to the ultimate "option = {}" assignment if you passed a falsy value (0, "", false), which is different than if you didn't pass a value (undefined). Which is resolved by "option = option === undefined ? option : {}", which is even larger and kinda ugly.
[+] [-] bzbarsky|14 years ago|reply
[+] [-] clintjhill|14 years ago|reply
GWT could be really strong. But it's this single maintainer problem that I think prevents it's penetration into the market.
Sadly when I hear people talk about the "strengths" of GWT, debugging and IDE debuggers is what I hear most. If that is the core reason for using GWT it seems shortsighted.
And for me personally I find that using Java (static typed system) to compile down to JavaScript (dynamic function system) is too big a paradigm switch for developers to maintain. Other languages, specifically functional type languages are far better for maintaining language paradigms in compiler situations.
[+] [-] grimlck|14 years ago|reply
I think the only way to defend against that is to have an open source project, and to have a sufficiently large user base such that someone is sure to take over if the owners drop the project.
I think the strength of GWT is that for some languages/teams, a statically typed language is more appropriate than a dynamic language. And isn't more choice a good thing? Avoid the whole 'this is a hammer, everything else is a nail' approach?
I do agree that some teams choose GWT for inappropriate reasons though.
[+] [-] Stormbringer|14 years ago|reply
Disclaimer: I've done GWT and I liked it.
I did not find any Java<->Javascript paradigm shift problem at all. You simply forget about the Javascript and just write Java.
The big benefit of using GWT over writing 'native' javascript is that you get the same behaviour on all browsers.
The big benefit of using GWT over using other java based web frameworks is that GWT moves the client's state down to the client, where it belongs.
If you look at most other Java web frameworks like that (e.g. Struts and it's direct competitors), they expend enormous effort porting data to and from the client, and trying to hack around the limitations of the HTML post operation - namely that blank values aren't returned (checkboxes!!) and that everything is passed as text (numbers!!). So what these other frameworks do is they end up making you write all these model objects, and then try to simulate the client state. JSF is the worst of these as it takes it the furthest, they're not just emulating the model, but also the view as well with their overly-complex de-hydration and re-hydration of components.
If you tell the client state to bugger off back to the client where it belongs, you save a good 30-40% of your typical web framework effort right there.
Eliminating Javascript browser/version idiosyncrasies saves you another 20-30% of your effort (more if the UI is very dynamic, less if it isn't).
-----
I think you're posting on the basis of assumptions you've made based on what you've heard about GWT, rather than experience with it.
[+] [-] bartl|14 years ago|reply
BTW an easy way to produce traditional class inheritance in Javascript is to have a single instance from the class you're trying to inherit from, as the prototype. (To work properly that object should be "abstract": have no ties to any physical resources, like a browser widget, a database handle or a file handle.)
[+] [-] masklinn|14 years ago|reply
I'm not sure why you're implying java's anonymous inner classes have much relation with class inheritance.
The vast majority of class-based languages do not have (or need) anonymous inner classes (though some languages allow for creating unnamed classes on the fly by instantiating metaclasses).
[+] [-] bgrohman|14 years ago|reply
http://www.prototypejs.org/learn/class-inheritance
http://dojotoolkit.org/reference-guide/dojo/declare.html
Plus, I tend to prefer prototypal inheritance to classical inheritance. I do agree that the constructor pattern using the new keyword and the prototype object is a bit odd, but that's not the only way to have objects inherit from other objects in javascript.
[+] [-] mark_l_watson|14 years ago|reply
[+] [-] EGreg|14 years ago|reply
Why must the language take care of everything for you when libraries can do it? That has been the case with C, C++ and other languages.
[+] [-] petermichaux|14 years ago|reply
[+] [-] skarayan|14 years ago|reply
[+] [-] rhizome|14 years ago|reply
[+] [-] AshleysBrain|14 years ago|reply
Then you can use whatever java-like/basic-like/functional-like language you want, and have it compile to bytecode. Also, with sophisticated JITs for that style of bytecode already lying around, you could probably instantly beat javascript's performance even under the best engines, because of static typing etc. rather than relying on ridiculously complicated static analysis.
It'd have to be supported side-by-side with javascript for the forseeable future, but the earlier you get a change like this in, the better...
[+] [-] azakai|14 years ago|reply
2. I don't think anyone but Microsoft would support .NET bytecode in the browser, simply because Microsoft controls .NET and has patents on it. It would take a lot more to reassure other browser vendors than Microsoft's existing CPs.
3. Running dynamic languages on Mono is slow. Look at the speed of all the dynamic languages on Mono (or the JVM for that matter), and compare them to native implementations of dynamic languages, in particular JavaScript and Lua. The native implementations beat dynamic languages on Mono by a large margin, simply because .NET is a bytecode made for static languages. Of course you can say that you prefer to have static languages in the browser over dynamic ones, that's a legitimate opinion of course, but not everyone would agree.
4. Standardizing on bytecode can inhibit innovation. JavaScript doesn't have a bytecode standard, which let JS engines implement very different ways of running it (V8 doesn't have a bytecode interpreter at all, for example). Of course standardizing on syntax also inhibits innovation, just in other ways, it isn't clear which is better.
5. Static languages compiled to JavaScript (that is, that use JavaScript as their 'assembly') are getting quite fast. Some benchmarks I ran found them to be around 5X slower (on the development versions of SpiderMonkey and V8) than gcc -O3, compared to Mono which is 2.5X slower, http://syntensity.blogspot.com/2011/06/emscripten-13.html
6. There is already Silverlight/Moonlight which does .NET in browsers, and it hasn't been very successful. (Of course it is a chicken and egg thing, if it were bundled in browsers it might be more popular. But the failure of Silverlight is a disincentive to add Mono to browsers nonetheless.)
For all these reasons, I don't think Mono has much of a chance to be included in browsers. Most of the same arguments apply to other static-language bytecodes like NaCl.
[+] [-] nxn|14 years ago|reply
Am I reading this right? Objective-J (2008), C# (2001), HaXe (2005), etc having compilers to javascript in 1997?
[+] [-] petermichaux|14 years ago|reply
[+] [-] TheOnly92|14 years ago|reply
[+] [-] kib2|14 years ago|reply
[+] [-] bengarvey|14 years ago|reply
[+] [-] mbrubeck|14 years ago|reply
Mobile processors are still slower than desktop ones, of course, but JavaScript on mobile today is already faster than JavaScript on desktop just a few years ago. For example, the benchmarks on http://arewefastyet.com/ show V8 running only about 5x slower on an nVidia Tegra 250 ARM board than it does on an Intel Core 2 Duo Mac Mini.
[+] [-] seanp2k|14 years ago|reply
Googling around, I see tons of misuse: Example of bad usage: "White Stripes are dead (long live white stripes)"
Example of proper usage: "Palm is dead; long live Palm!" (this would mean that Palm got acquired or reformed) "Paper is dead; long live paper!" (could be proper if used in an article about how paper for PRINTING is dead but paper lives on in other forms)
REF: http://en.wikipedia.org/wiki/The_King_is_dead._Long_live_the....
[+] [-] petermichaux|14 years ago|reply
[+] [-] unknown|14 years ago|reply
[deleted]
[+] [-] derrybryson|14 years ago|reply
[+] [-] johnx123|14 years ago|reply
[deleted]