I cannot find the reason why my app does not work when compiled to JavaScript using dart2js. I have tried debugging my compiled JavaScript app using Google DevTools but found it very difficult to understand both the debugger and JavaScript code. You can find my web app on GitHub. I suspect there is a conflict between compiled JavaScript code and imported third party JS libraries such as jquery but not sure. I highly appreciate your help.
The easiest is probably to add a few print statements into your code. With binary search it should be relatively easy to figure out when the VM and dart2js diverge.
Please report back, what the reason was and/or file a bug at http://dartbug.com/ if you believe that dart2js did it wrong.
Solution (as reported by OP): "dart.js should come after [the] app script line".
Related
I'm trying to get a number of Chrome extensions working in an Electron app. Electron only supports dev tools extensions, so I'm writing code to handle regular extensions more-or-less from scratch. But, I'm getting stuck figuring out what's involved in getting the content scripts to run in the same way they do in Chrome.
In the existing Electron implementation, which is expressly limited to development tool extensions, I traced the code to here, specifically, line 392:
win.devToolsWebContents.executeJavaScript(Extensions.extensionServer._addExtension(${JSON.stringify(extensionInfo)}))
Finding the next step in this process has proved very challenging. I think, but am not certain, that HERE is the corresponding Chromium code, but this seems like it's for development tools extensions in particular (what with the calls to InspectorFrontendHost and the use of iframes).
Could anyone point me in the right direction? Where is the code where Chromium loads the content scripts for regular extensions? Or is this that code?
I'm probably missing something very basic here, but I've spent quite a while searching for just about any term I could come up with.
I wanted to check out Dart and Dart.Polymer, so I grabbed some examples from various tutorials. I managed to get everything working, but it seems ALL HTML/JS/CSS content from custom Polymer elements and paper-/iron-/... elements get pasted to index.html, along with various other JavaScript stuff.
This leads to my index.html being 16.000+ lines long in release mode builds, (20.000 in debug) in this Dart Academy Tutorial, and here is the corresponding source in GitHub
The tutorial also links to a live version that has pretty HTML/imports.
The same happens with the basic Polymer sample project in Webstorm.
My different setups:
Windows 10 and Ubuntu 14.04 (tried both)
Dart SDK current stable and dev version
pub build --mode:release and debug, from commandline and within Webstorm
various transformers, various orders, various dependency versions in pubspec.yaml
Aside from the index.html file my output folder seems fine, elements are present in e.g. output_folder/build/web/packages/polymer_elements/.
I know that everything that is compiled into the index is necessary, but why does it not generate links to the files in the created build/polymer_elements folder? I assume it is possible and the live versions of the examples I found have not been edited manually to link to all elements and scripts and cut them from index.html. I know it probably does not even affect load times in a significant way, but it still bugs me.
Thanks for any help in advance, don't be shy to point out if I read over something very basic or just did not search for the right term :D
This is a deployment optimization, similar to the vulcanize tool for polymer js, except that its the default in Dart. Html imports create tons of extra requests which is slower than just downloading the one large file.
Inlining transformed code (JS/CSS) is normal behavior and none of the options to dart2js will affect this.
I believe the demo output linked in the tutorial you mentioned was unfortunately not the actual dart output. I believe https://polymer-checkout.firebaseapp.com/ is a demo of the original polymer version, not the dart version.
electron, node-webkit, brackets-shell and atom-shell are frameworks that allow a user to create stand alone executables that use HTML, CSS, and JavaScript (Node) for all code in the app. They don't require any prior installation of any software, as I understand it. I want to use Dart instead of JavaScript. I don't want a chrome app because that requires the installation of Chrome, if I understand correctly. Is it possible to make a stand-alone application using Dart? Will DartToJs be able to do this for me?
You need to have a Dart-VM (Dart-Runtime) installed in order to be able to execute Dart applications on the command line/server.
As far as I know there is no way to create a standalone executable, at least no easy one.
It is technically possible to create an executable that contains the Dart-VM but there are no tools available yet that generate that for you.
I don't think the path using Dart2JS will help much. Dart2JS aims primarily at browsers but I have heard that some try to use Dart2JS to run Dart code with Node.js but I don't know if that really works.
This similar question contains some links that may be of interest to you: Embedding Dart into application
dart2js + node-webkit will definitely do this for you. Just compile your webapp to js, make a proper package.json file and follow the standard directions on the node-webkit github page.
There's even a pub package that let's you use the node-webkit API from dart (filesystem access, window controls, and whatnot).
Search pub for node_webkit and you'll find it.
Good luck.
Is there a REPL for Dart to experiment with?
I tried inputing dart code in DevTools in Dartium and that also didn't work.
So I couldn't find an easy way to play with various APIs in dart.
I tried inputing dart code in devtools in Dartium and that also didn't
work.
I'm very new to Dart, but something I came across was that you CAN evaluate code in Dartium. In order to do so, you must first load a page with Dart code in it and then toggle this selector in the console from "javascript page context" to one that references a Dart package or Dart code.
Once you do that you should be able to execute Dart in the console:
As a VIM user, I hardly have to open the Dart Editor now :). I should also mention that breakpoints, hovering over stepped into code to get variable details, navigating the call stack, and some level of intellisense in the console also work. I couldn't get conditional breakpoints to work, though.
Though it is not really a REPL, you may find the Try Dart online tool useful for playing around. It's a bit slow, since it is actually compiling the Dart code to JavaScript in order to have it work within the browser.
There is also a console that someone built, which is probably better if you're looking for a real REPL, but it requires a bit of setup.
There is an announcement about REPL for Dartium - see Nathanial's comment below. There are plans for Smalltalk like super-REPL. Here is what Gilad Bracha (member of the Dart team at Google) wrote on this subject in Is there a REPL or console for Dart:
"I don't see this as a language question at all. It is a matter of tooling and reflective library support. With proper mirror builder APIs, building a REPL would be trivial. As it sands right now, it can be quite challenging. And of course, REPL is not the ultimate goal - there are more advanced interactive tools, like workspaces in Smalltalk/Self/Newspeak, where you not only evaluate things interactively at some top level, but can inspect the resulting objects, evaluate within the scope of an individual declaration or object etc. I am sure we will get there in time - and i much prefer sooner than later."
The correct answer is https://dartpad.dev/
That site didn't exist when the other answers were posted in 2013, but you've stumbled on this post after 2020. And now you know. https://dartpad.dev allows you to create and share new Dart snippets and even put them in a Flutter app running online. Very, very cool!
Since 2022.10.22, there is a REPL for Dart: https://github.com/fzyzcjy/dart_interactive :)
Features:
Use any third-party package freely
Auto hot-reload code anywhere, with state preserved
Supports full grammar in REPL
Play with existing code side-by-side
Disclaimer: I wrote that package.
i was looking at several lua/objective-c implementations that looked promising for a project i want to create ,but with an exception that i wanted to be able to download the scripts at runtime.Then i found the terms which state :
"An Application may not download or install executable code. Interpreted code may only be used in an Application if all scripts, code and interpreters are packaged in the Application and not downloaded. The only exception to the foregoing is scripts and code downloaded and run by Apple's built-in WebKit framework."
so clearly you cant download any lua scripts at runtime.
If i interpret correctly you can only run javascript files downloaded through UIWebView.
So if i wanted to create a objective-c/javascript bridge through uiwebkit(with stringByEvaluatingJavaScriptFromString and url encodings) ,i dont see anything against apple's term right?do you think it would be an overkill in perfomance?
I have no experience about the performance of executing Javascript through UIWebView, but I suspect the toll is high if you plan to call stringByEvaluatingJavaScriptFromString with fine grained code. On the other hand, nothing keeps you from loading a full HTML in your UIWebView with all the Javascript code that you need, and this approach would certainly ensure better performance.
actually, there is an alternative approach that you can try and follow. It is actually possible to directly embed the WebKit Javascript Engine (Javascript Core) into your app. This approach has already been "approved" by Apple and you can find it described here. (Dominic Szablewski, the creator of the JavaScript game engine Impact, is the guy who accomplished this).
In short, it comes down to compile the Javascript Core as a static library and then link this in your app. If you don't feel like compiling it yourself, at the link I posted you can also find more information as to how you can license the library from Dominic Szablewski. (I am not really suggesting anything at this respect, just summarizing information).