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Comment by sultezdukes | Hacker News Reader

It's a pretty smart move that Microsoft did with TypeScript, making it a proper superset of JavaScript. Google seems to be stuck in the past, bringing out its own VM that is a complete non-starter, and making another class-based, Java-like language. I guess Google is going down the road that Microsoft did years ago with flinging feces on the wall and see what sticks.

I have nothing against Dart. I played with it a year and a half ago when the Eclipse beta came out. It's nice tooling, but brings absolutely nothing interesting to the table.

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Yesterday, I rewrote one of my JS modules into Dart, and it ended up being about 10 lines of code with only two modules imported. Then I compiled it to JS, and it was over 120k. I tried for about an hour to get that down to a reasonable size with Closure Compiler/Uglify, but the names were too wonky.

I'm sure that, given enough time, they'll solve these problems, but as for right now... it isn't ready for primetime. Not by a longshot.

You don't say if you used the 'dart2js --minify' setting, but Closure Compiler should do well. The --minify flag leaves alot more room for additional minification. You say you used two modules. The result really depends on the modules. For example, the Dart/JS interop module adds about 140K un-minified. Tree shaking is always on, so the 140K is after stripping unused code. I initially jumped into Dart because I was interested in doing packaged apps that run locally, so the size over the wire didn't concern me as much. I recently converted an ActionScript app to Dart and the post-minify Dart was around the same size as the compiled .swf file (for comparison, same functionality)

Seth Ladd has a couple of posts about Tree Shaking and Minification if you're interested http://blog.sethladd.com/2013/01/minification-is-not-enough-... http://blog.sethladd.com/2013/03/i-shrunk-my-dart-to-js-code...

> You don't say if you used the 'dart2js --minify' setting

I did. I'm no stranger to Closure Compiler, and even after fiddling around with ADVANCED_OPTIMIZATIONS for an hour, those ridiculous $variables persisted. What was even weirder was, just as a test, I imported a module I wasn't even using at all, and for some reason, Closure Compiler still refused to remove its code...

Just for grins, I compiled the Dart app I'm working on now with --minify. It went from 530K to 240K. Then I cleared the --minify flag and used the Closure Compiler but it failed with errors. Not sure what is going on yet, but I don't think this is necessary or advisable -- I've never read of anyone using the Closure Compiler with Dart. Here is a sample few lines from --minify. It's fairly minimal.

function I(){} init() var $=I.p var $$={}

Okay, but um, why did minify not get rid of the module i wasn't even using?

Just to be clear, here is what I did.

  Dart source -> dart2js -> JavaScript (530K) 
  Dart source -> dart2js -> JavaScript (530K) -> Closure Compiler -> *error*  
  Dart source -> dart2js --minify -> JavaScript (240K)

If I import a module and don't use it, such as 'dart:utf', the resulting JavaScript output size does not go up. If I call a function in dart:utf the JavaScript size goes up. If I stop calling the function, the size goes down. If I create a function but don't call it, the size stays the same. If I call it, the size goes up. Everything seems to be working. They just release a new version a few days ago and I'm on the latest.

--minify is still being improved and is not complete yet. As well, you need to say what libs you included. If you import "HTML" it is basically like including jquery.

Right, but the great thing about a compiled language like Dart is that it can detect at compile-time which modules aren't being used and then exclude those from the js output. Except, it doesn't seem to ever do that.

EDIT: Well, technically, Dart is actually designed to be interpreted (or JIT compiled, or what have you) by the Dart VM, so calling it a "compiled language" was incorrect on my part. However, dart2js is a compiler, so, it should be doing compiler-y shit.

Tree-shaking is the term for removal of uncalled functions. The minifier is still early on so expect it to get better with time.

I think of the Dart VM as a dev tool. The goal is to use dart2js for production output. The Dart VM will eventually be very useful in Chrome Packaged Apps once Chrome has it built in. Google has a ton of experience with Google Web Toolkit to write JavaScript apps such as Gmail in Java. Dart is branch of that evolution. I am not even sure if they care all that much if the rest of use it. It seems to me an internal tool that they've open sourced. I see no plans to force it on the market.

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