Browser based gaming is the hot thing going right now but doesn’t mean we should do it too - being trendy doesn’t mean being good or being the best game play aid option available which should be the goal and I don’t see being browser based meeting that criteria based on the browser game apps I’ve seen already. They are really quite crappy in one way or another.
I’ll reserve my other thoughts - still thinking about everything else
wxWidgets suggested by Michael looks like a good cross-platform framework. It looks to me like higher level entry for developers though, so I don’t know if the developers could/would make that step.
I checked out freeciv.net, done in HTML5 this week, and was very impressed. But it runs the game processes on the server. I can’t imagine that would be what you’d want, more server strain. The code to do it is complex, and that only runs 1 kind of game! Please don’t consider JavaScript, it’s great for scripting web pages, but not for complex applications like this. JavaScript is interpreted code, so you will get a huge performance hit from that alone. You’d also need to use some other means for the “GUI” with JavaScript, so you’d end up with browser dependent display code (DHTML/CSS) which breaks every few months with updates. Despite the hype nothing serious gets written like this. You have web games, but they are either flash and/or very very simple. There is google apps, but although nicely done, they do nothing as complex as VASSAL. HTML5 adds a lot of features, but is far from final and there is inconsistent support for it. Instead of JavaScript you could write an application in Flash/Flex or Silverlight (ZunTzu 2 is planned to use Silverlight), but the step to just making a desktop app with much more flexibility in what you can do is small.
Hi all!
I’m the developer of OpenSettlers, a game engine specific to design Settlers of Catan games written in Java. It contains a reference implementration of a SoC client using GWT ui codebase. GWT compiles Java to Javascript, enabling me to write java, but have a complete browserbased game. An alpha demo is up at opensettlers.sourceforge.net. Keep in mind that it’s an alpha demo (lotsa bugs, looks still ugly), I will upgrade it in the coming weeks to a much more playable version.
In this post, I will outline some of the design decisions and implementation strategies I used. I hope they inspire the Vassal team for the implementation of the v4 release.
Seperation of UI/data
The codebase of OpenSettlers has the seperation of concerns (ui and data). I have defined interfaces for most things, implementation of these interfaces use a “SimpleEventBus” to propagate changes in the objects. That way UI objects can subscribe to changes in the data. A truly seperated should be able to have different UI implementations. Currently, OpenSettlers has this: It uses SVG to draw the gameboard as only implementation. If you like code, here are some links to the Robber implementation (a robber can move, and has a location property):
Robber class:
github.com/generateui/OpenSettl … obber.java
Moved event:
github.com/generateui/OpenSettl … Event.java
Moved event handler:
github.com/generateui/OpenSettl … ndler.java
EventBus interface and SimpleEventBus are classes from GWT, but these are extracted from another project, code.google.com/p/simpleeventbus/. It should be easy to build a custom one for Vassal.
As OpenSettlers is mainly focused on offering a webbased playing experience, I’m writing code for GWT UI only. However, a dev wanting to make a swing or JavaFX would only need to implement a set of interfaces already defined. A browser itself offers a few possibilities also to write UI in: HTML, canvas, canvas3d (WebGL), SVG and flash. As such, a 3D version of OpenSettlers would be trivial to add, only the defined interfaces should be implemented, similar to adding a swing or JavaFX implementation. The data classes can be reused among those UI implementations. OpenSettlers is based on GWT 2.1, when it upgrades to GWT 2.2, I will add support for the canvas drawing, which only involves adding about 10-15 classes which implement the defined interfaces.
Abstracted definition of data
Another point of Uckelman is using another way to store the data into files. Uckelman proposed XML as a way of doing this. OpenSettlers has the same problem: the classes only consisting of data (no behaviour/methods) must be defined, and then some serialization technique should be added in order to read/write this data from disk/ssd. The solution I will use will be protobuf: code.google.com/p/protobuf-gwt/. Protobuf lets you define those dataclasses in a DSL, resulting in a set of protobuf files containing the definition of all dataclasses. With this platform and language independent definition, you have a basis which you can use ANY serialization technique with. Whether that’s XML, Java, Json, RelaxNG, plain text, it does not matter. Currently serializers exist for quite some languages, included the noted ones (XML, Json etc).
Some examples why this will benefit OpenSettlers:
I’d like to store some data into the local browser storage. For instance, I’d like to save board definitions of OpenSettlers locally, to prevent redownloading them each time a player connects to a server. I have an interface Board, with a corresponding implementation BoardImpl. To do this without protobuf, I must either create a new class taking a Board, then manually write code to serialize this to Json in order to write this to the local storage in the browser. I must do this for every data class definition I want to store into the local browser storage. When the definition changes, I need to update this manual code, you get the idea.
Instead, protobuf solves this for me. Using a generator, a Json implementation of the data class is generated from the protobuf definition. No need to write a single line of code. This would be no different when using XML.
I get very excited when I realize other SoC projects can reuse the protobuf defnition. Pioneers is such an implementation, written in C. It would be a matter of applying a C generator (which exists) to the protobuf definition. This generator then generates the dataclasses in C. If Pioneers would do this, Pioneers and OpenSettlers would become compatible. So, it not only saves writing manual code, it also allows to have a “standardized protocol”. No matter what language or platofrm is used: as long as a generator exists, it’s compatible. When no generator exist, it’s not very hard to write one. Lots of generators already exist.
I’m planning to add protobuf in a few weeks. It would be much better when I started with protobuf, but I only learned of them far in the implementation process. As OpenSettlers isn’t out of alpha yet, not all is lost .
My personal preference: I very much dislike XML, but like Json much more. That’s fine: a Json file will do just as good as an XML file. As long as there is a platform independent way to describe the data and then generate code from it, it’s just a matter of adding a generator to support another serialization technique.
GWT
Google Web Toolkit is not only a Java to Javascript compiler. It’s also a “set of best practices”. In working with GWT for about 6 months now, I came to learn that GWT is created with the unix philosophy in mind. Basically, GWT is a set of small, focused libs. Not only did I learn a lot of GWT specific stuff, but also lots of good idea’s, practices and good quality code. Examples are the ModelViewPresenter paradigm, handling of resources and RequestFactory.
GWT defines an application in three folders: shared, client and server. This makes sense: Seperating the code shared among the client and server, the client UI code, and the server specific code. You’re not forced to do it like this, but it turned out to be quite clarifying.
Vassal & OpenSettlers
I have looked to use Vassal for OpenSettlers to avoid writing code which I can reuse from Vassal. Uckelman describes the problems very accurately for why I dismissed it (for now). As parts of Vassal and OpenSettlers are pretty much alike, it would make sense to reuse those parts. When v4 successfully addresses above noted problems with the codebase, I’d very interested to reuse/include Vassal code into OpenSettlers. If solutions for the mentioned problems fall in my domain of expertise, I’d be happy to help with the transition, too.
I hope I add my 2 cents with this contribution. Greetz, generateui.
First of all, wxWidgets is indeed cross-platform, but: it’s still platform dependant, as currently every UI library is platform dependant. Namely: wxWidgets is dependant on the wxWidgets platform. This may sound a bit weird, but the current state of UI toolkits is that none of the toolkits/libraries implement a set of standardized interfaces. Truly platform independance would be achieved by having a set of interfaces for widgets/behaviour defined, and then implemented in the various libs/toolkits. Example: Say I make a login window. I HAVE to tie the code in the loginwindow to the UI lib. I cannot define an instance of interface Button. Instead, I have to define wxButton, or gwtButton, or javafxButton. If I’d be able to define a
private button Button;
, i can have the instance of the button be polymorphic.
GWT is a different beast. It can support Javascript, without ever working with javascript code directly. Modern browsers such as Chrome and Firefox actually compile javascript objects into anonymous classes, which are then consumed by the javascript engine. This results in very fast code execution. You can say the old IE <8 and FF <3 engines are indeed code interpreters, but newer engines lean towards JIT compilation, like Java or .NET. Especially for boardgames, performance is not really an issue. The above link to OpenSettlers demo uses 1MB of minified javascript code (!). That’s a lot of interpretation. When loading locally from SSD, loadtime on a single core 1.5Ghz is below 1 second. That’s surely acceptable. And I even have not yet optimized the OpenSettlers code yet. There’s a huge set of classes which are not really necessary, but are compiled by GWT nevertheless because I needed only a few classes.
GWT only supports features which work in all major browsers. That’s the reason SVG is not yet supported: it’s implementation in the different browsers is not yet on par for every major browser. On the other hand, canvas is supported by the major browsers, and as such supported by GWT 2.2.
As I noted in my previous post, when there is a UI agnostic codebase, it doesnt matter if you want to use SWT of GWT of JavaFX or flash or whatever.
We would never be able to be completely platform neutral as the VASSAL
engine relies on a very wide list of libraries. What you describe would be
very limiting. Although it sounds like a good idea, we would only be able
to support the lowest common denominator with respect to both platform and
browser. That’s great for small apps or very restricted ones, but I can see
us hitting brick walls a lot.
As for JavaScript itself, I see dynamic typing as a debugging nightmare.
We’re actually trying to go in the opposite direction with better defensive
programming practises. In addition, we’re currently looking at ways to
expand our capabilities not restrict them further (e.g., better graphics/3D
engine).
With respect to a C-based language, conversion from Java is relatively
straightforward excepting the UI. JavaScript has a lot of scoping issues
that make a straight translation very tricky.
I think the frontrunners are still the status quo (Java+Swing), Java+SWT,
Qt, or wxWidgets. They all have their problems, but having to rely on a
webbrowser (who might later decide that a feature we’re using is actually an
annoyance) would create more problems in terms of support. Right now, we
support Windows, Mac, and Linux directly, but I can’t imagine supporting
multiple web browsers and all the problems they introduce.
On 27 March 2011 12:43, generateui rtimon@gmail.com wrote:
wxWidgets suggested by Michael looks like a good cross-platform
framework. It looks to me like higher level entry for developers
though, so I don’t know if the developers could/would make that step.First of all, wxWidgets is indeed cross-platform, but: it’s still
platform dependant, as currently every UI library is platform
dependant. Namely: wxWidgets is dependant on the wxWidgets platform.
This may sound a bit weird, but the current state of UI toolkits is that
none of the toolkits/libraries implement a set of standardized
interfaces. Truly platform independance would be achieved by having a
set of interfaces for widgets/behaviour defined, and then implemented in
the various libs/toolkits. Example: Say I make a login window. I HAVE
to tie the code in the loginwindow to the UI lib. I cannot define an
instance of interface Button. Instead, I have to define wxButton, or
gwtButton, or javafxButton. If I’d be able to define a Code:
private button Button;, i can have the instance of the button be polymorphic.
Please don’t consider JavaScript, it’s great for scripting web pages,
but not for complex applications like this. JavaScript is interpreted
code, so you will get a huge performance hit from that alone. You’d
also need to use some other means for the “GUI” with JavaScript, so
you’d end up with browser dependent display code (DHTML/CSS) which
breaks every few months with updates. Despite the hype nothing serious
gets written like this. You have web games, but they are either flash
and/or very very simple. There is google apps, but although nicely
done, they do nothing as complex as VASSAL. HTML5 adds a lot of
features, but is far from final and there is inconsistent support for
it. Instead of JavaScript you could write an application in Flash/Flex
or Silverlight (ZunTzu 2 is planned to use Silverlight), but the step
to just making a desktop app with much more flexibility in what you
can do is smallGWT is a different beast. It can support Javascript, without ever
working with javascript code directly. Modern browsers such as Chrome
and Firefox actually compile javascript objects into anonymous classes,
which are then consumed by the javascript engine. This results in very
fast code execution. You can say the old IE <8 and FF <3 engines are
indeed code interpreters, but newer engines lean towards JIT
compilation, like Java or .NET. Especially for boardgames, performance
is not really an issue. The above link to OpenSettlers demo uses 1MB of
minified javascript code (!). That’s a lot of interpretation. When
loading locally from SSD, loadtime on a single core 1.5Ghz is below 1
second. That’s surely acceptable. And I even have not yet optimized the
OpenSettlers code yet. There’s a huge set of classes which are not
really necessary, but are compiled by GWT nevertheless because I needed
only a few classes.GWT only supports features which work in all major browsers. That’s the
reason SVG is not yet supported: it’s implementation in the different
browsers is not yet on par for every major browser. On the other hand,
canvas is supported by the major browsers, and as such supported by
GWT 2.2.As I noted in my previous post, when there is a UI agnostic codebase, it
doesnt matter if you want to use SWT of GWT of JavaFX or flash or
whatever.
As Vassal is written in Java, Vassal ties itself to the Java platform, which depends on… the JVM (Java platform). I’m very curious about the limitations you see towards the things I describe. As I see GWT as a few things, I also see GWT as a GUI library. From that perspective, It would not be limiting, but just another option to perform the GUI implementation with.
To build further on the Robber code example links I posted: I have an SvgRobber, but as well I can make a CanvasRobber or Canvas3DRobber. All XxxRobber classes implement RobberVisual and subscribe to the MovedEvent to change their [x,y] location. The Robber behaviour and data is seperated into a Robber class, and abstractly defined in RobberVisual interface and implemented in SvgRobber class (or the future CanvasRobber class).
See for RobberSvg: github.com/generateui/OpenSettl … erSvg.java
If you explicitly do not support IE, you can have most cake and eat it too.
Exactly. That’s why GWT worked out for OpenSettlers so well. No dynamic typing, good IDE support, and improved capabilities for the UI (such as canvas, canvas3d (WebGL), html and SVG).
I’m not sure if you’re replying on me, or a previous post. I only talked about C with Pioneers as example, so I assume you’re not replying with above quote to my post.
The point of Uckelman is to decouple classes currently tightly coupled to SWT from the UI toolkit, seperate UI classes from other classes. When that’s done, it does not really matter what UI toolkit one uses. OpenSettlers uses currently 2: an external SVG library, and the GWT widgets. As the architecture of OpenSettlers explicitly supports this using interfaces (loosely coupled design), I can make widgets in SWT, GWT, JavaFX, Canvas, SVG, whatever I like. The question indeed would be what UI library Vassal would support officially, which I should not answer as I am not part of Vassal.
Your last sentence make me believe that what GWT does is not fully understood. Applications written with GWT are entirely written and debugged in java and your favorite IDE. GWT contains a compiler which translates Java to Javascript, so a user can run the application in the browser. GWT makes different permutations for each browser, to ensure the small (and sometimes big in the case of IE) differences are taken care of. That’s something GWT does by default, nothing which the programmer needs to do. I have actually not written a single sentence of javascript, though OpenSettlers still runs 100% natively (no flash/java applet, 100% html/javascript/css) in the browser. By using GWT, I have a single codebase, and I can support any browser, device (as long as it has a modern browser, like Android and IOS devices) and resolution (abstracted UI in OpenSettlers takes care of this). I don’t have to worry about OSes, since the browser itself abstracts the OS. Apart from the SVG element (GWT 2.2, which supports canvas, removes the need for SVG), I have not yet found any crossbrowser bugs. Crossbrowser support is handled by GWT, not by the programmer coding against GWT.
I am no contributor for Vassal, so the things I share on this forum are just FYI. It’s just my experience devving on a codebase in many aspects similar to Vassal’s. I don’t own Google shares, I’m just a techdude sharing learned lessons 
Making all of VASSAL web-based, even if it runs mostly in client-side Javascript, will still add strain to an already strained server, and does not solve the single point of failure. If VASSAL must be redone as a web-based platform it must use technology which can run offline (when the server goes down). That leaves HTML5, Adobe AIR/Flex, MS Silverlight. HTML5 is completely unready. Adobe AIR runs on all currently supported platforms, but it basically a fancy Flash app, and I don’t think it is suitable. MS Silverlight I think might be suitable someday, but it does not support Linux. The developer of ZunTzu is looking at Silverlight for ZunTzu 2, but I think it will be a tough nut to crack, and ZunTzu does a whole lot less than VASSAL. While there are some fancy web-apps out there, they all rely on their server and are all custom programmed to support one single game/task.
Bottom line is that I don’t feel that all things considered there is any argument that makes web-based make more sense than a more suitable technology. You find the tools to fit the solution, not fit the solution around the tools. If you make it web-based, you force it through because you feel it must be web-based. Desktop applications provide a richer framework and more offline flexibility. Whats important is choosing one that works best on all three currently supported platforms, is easiest to expand to other platforms (iOS/Android/…), and is easiest for the developers to implement all the existing and future desired features (2D/3D graphics, modules and extensions, Python event scripting, …).
I am not a developer either, so my contribution to this thread is all FYI too. I make desktop and web apps. Completely different field from VASSAL, but code is code 
.
Thus spake Michael Kiefte:
As for JavaScript itself, I see dynamic typing as a debugging nightmare.
We’re actually trying to go in the opposite direction with better defensive
programming practises. In addition, we’re currently looking at ways to
expand our capabilities not restrict them further (e.g., better graphics/3D
engine).
I was curious to see what could be done with JavaScript as it is now,
so I worked up two demos over the weekend, one using the HTML5 canvas,
and one using regular DHTML techniques. I’ve put the demos here for you
to try:
vassalengine.org/~uckelman/js-test.tar.bz2
vassalengine.org/~uckelman/js-test.zip
(Both archives have the same content, download the one you prefer.)
Once you’ve unpacked the archive, browse to launch.html, where you’ll
find a link to each of the demos. In each demo, you should be able to
drag around the pieces. In the elements demo, dragging on the map pans
it.
I learned a few things by doing this:
Also of note here is the fact that every canvas example I was able to
find on the web assumes that you’ll have about 10 objects on your
canvas, so does collision detection by searching the whole object list
and testing each one for hits, and also repaints the whole canvas every
time something changes. If you do either of these, instead of using a
quadtree for collision detection and repainting only changed regions,
you can’t even get a 1000x1000 canvas to work well with 100 objects on
it.
–
J.
Hi Joel,
Why did you comment out mapZoom(e)?
On 28 March 2011 09:13, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
As for JavaScript itself, I see dynamic typing as a debugging nightmare.
We’re actually trying to go in the opposite direction with better
defensive
programming practises. In addition, we’re currently looking at ways to
expand our capabilities not restrict them further (e.g., better
graphics/3D
engine).I was curious to see what could be done with JavaScript as it is now,
so I worked up two demos over the weekend, one using the HTML5 canvas,
and one using regular DHTML techniques. I’ve put the demos here for you
to try:vassalengine.org/~uckelman/js-test.tar.bz2
vassalengine.org/~uckelman/js-test.zip(Both archives have the same content, download the one you prefer.)
Once you’ve unpacked the archive, browse to launch.html, where you’ll
find a link to each of the demos. In each demo, you should be able to
drag around the pieces. In the elements demo, dragging on the map pans
it.I learned a few things by doing this:
- The canvas demo is unusable for me. It turns out that this has
nothing to do with the huge map image—it’s just as bad when there’s
no map image. What does matter is the size of the canvas. It works well
for me at 1000x1000, but 8000x3000 is 24 times larger. I don’t know how
the canvas is implemented in Firefox 3.6.16, but it seems that they’re
not using algorithms which scale up well.Also of note here is the fact that every canvas example I was able to
find on the web assumes that you’ll have about 10 objects on your
canvas, so does collision detection by searching the whole object list
and testing each one for hits, and also repaints the whole canvas every
time something changes. If you do either of these, instead of using a
quadtree for collision detection and repainting only changed regions,
you can’t even get a 1000x1000 canvas to work well with 100 objects on
it.
- The elements demo works well for me. It’s also 245 lines of code, 41
of which are just HTML. The reason it’s so small is that all I had to do
was write event handlers for some mouse events. The browser is already
providing all of the collision detection, repainting, drag and drop,
and image loading. We have thousands of lines of code in VASSAL for doing
essentially the same thing.–
J.
Thus spake Michael Kiefte:
Hi Joel,
Why did you comment out mapZoom(e)?
Uncomment it and see.
I couldn’t get it to work well enough using CSS scaling to be usable.
I had a third idea which I ran out of time to try, which is to do
everything inside of SVG, where you’ve got (presumably) better-
supported scaling and rotation. Since SVG is part of the DOM, it
wouldn’t be much different from the code you’re looking at.
–
J.
OpenSettlers does not rely on the webserver for hotseat games and botgames, it runs completely offline as an independent webapp. Off course, when you want to play against other players, a server is necessary.
A p2p server is also a problem for OpenSettlers, see the #1 issue: github.com/generateui/OpenSettl … es#issue/1 . ipv6 might fix this partially (no more NAT portmapping horror), as homeserver platforms like Windows Home Server, Amahi and others might solve this problem too.
The thing about webservers is that afaik, they are built to scale. I don’t have any realworld experience with high loads, but I can imagine it can be easy to add servers and balance the load. It’s in the very DNA of webservers to do this. WebSockets might be a little different beast though, as it’s relatively new and doesn’t really fit in the ‘fire and forget’ nature of handling stateless requests.
When I set out to write OpenSettlers, I had 2 requirements: 1. All variants of the game should be able to be implemented, 2: Users should have no barrier to play.
1 is not interesting in this topic, but 2 is. I came at GWT because a webapp offers the lowest barrier for users to participate. To play, the only thing needed is to enter an URI and click a button. No other platform could and can offer me this: Java applets require JVM install, flash requires the flash plugin, native apps require the traditional download-install-configure process.
The application server must be a ‘native’ application, as there is no way to accept connections in a web browser without plugins. That’s why I plan to offer a central server to play games, but also a central metaserver to list gameservers.
Some choice quotes regarding JavaScript on the Mozilla website that made me
cringe:
JavaScript is a small, lightweight language; it is not useful as a
standalone language, but is designed for easy embedding in other products
and applications, such as web browsers.JavaScript is a very free-form language compared to Java. You do not have
to declare all variables, classes, and methods. You do not have to be
concerned with whether methods are public, private, or protected, and you do
not have to implement interfaces. Variables, parameters, and function return
types are not explicitly typed.In expressions involving numeric and string values with the + operator,
JavaScript converts numeric values to strings. For example, consider the
following statements:
1x = “The answer is " + 42 // returns “The answer is 42”
2y = 42 + " is the answer” // returns “42 is the answer”In statements involving other operators, JavaScript does not convert
numeric values to strings. For example:
1"37" - 7 // returns 30
2"37" + 7 // returns “377”Another unusual thing about variables in JavaScript is that you can refer
to a variable declared later, without getting an exception.If an array is created using a literal in a top-level script, JavaScript
interprets the array each time it evaluates the expression containing the
array literal. In addition, a literal used in a function is created each
time the function is called.
That’s just the from first three pages. I’m actually going to learn
JavaScript anyway as I wouldn’t mind using it for some lectures (I use
pdfLaTeX + Beamer and you can embed JavaScript in the resulting PDF). But
it kind of reminds me of MATLAB or perl – not something that you’d want to
do a really big project in. (However, I have done really big projects in
MATLAB and they’re a nightmare to debug).
On 28 March 2011 09:35, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
Hi Joel,
Why did you comment out mapZoom(e)?
Uncomment it and see.
I couldn’t get it to work well enough using CSS scaling to be usable.
I had a third idea which I ran out of time to try, which is to do
everything inside of SVG, where you’ve got (presumably) better-
supported scaling and rotation. Since SVG is part of the DOM, it
wouldn’t be much different from the code you’re looking at.–
J.
So did I.
Running the Canvas test doesn’t work - “This text is displayed if your browser does not support HTML5 Canvas.” As one would expect if you are running IE8 or lower which will be at least 60% of the world
The element test does not work in IE8 either. I can only see the top left corner of whatever is being displayed “Axis Air Points”. see no pieces, cannot scroll the map etc…
too many different browser issues to deal with going this approach
I just had to post this bit. You’re allowed to have an array of length 5 in
which the myArray[3] is invalid following delete myArray[3]; Object
properties seem unmanageable and methods are implemented rather poorly (you
have to assign them like variables). JavaScript seems fine for small
projects where you’re the only developer, but for multi-developer projects,
it would be hard to coordinate. I really can’t imagine working with this for
anything complicated.
From the docs:
At the implementation level, JavaScript’s arrays actually store their
elements as standard object properties, using the array index as the
property name
Didn’t sh used to work like this? I guess there’s a reason why it’s called
JavaScript.
On 29 March 2011 15:22, Michael Kiefte mkiefte@dal.ca wrote:
Some choice quotes regarding JavaScript on the Mozilla website that made me
cringe:JavaScript is a small, lightweight language; it is not useful as a
standalone language, but is designed for easy embedding in other products
and applications, such as web browsers.JavaScript is a very free-form language compared to Java. You do not have
to declare all variables, classes, and methods. You do not have to be
concerned with whether methods are public, private, or protected, and you do
not have to implement interfaces. Variables, parameters, and function return
types are not explicitly typed.In expressions involving numeric and string values with the + operator,
JavaScript converts numeric values to strings. For example, consider the
following statements:
1 x = “The answer is " + 42 // returns “The answer is 42”
2y = 42 + " is the answer” // returns “42 is the answer”In statements involving other operators, JavaScript does not convert
numeric values to strings. For example:
1 “37” - 7 // returns 30
2"37" + 7 // returns “377”Another unusual thing about variables in JavaScript is that you can refer
to a variable declared later, without getting an exception.If an array is created using a literal in a top-level script, JavaScript
interprets the array each time it evaluates the expression containing the
array literal. In addition, a literal used in a function is created each
time the function is called.That’s just the from first three pages. I’m actually going to learn
JavaScript anyway as I wouldn’t mind using it for some lectures (I use
pdfLaTeX + Beamer and you can embed JavaScript in the resulting PDF). But
it kind of reminds me of MATLAB or perl – not something that you’d want to
do a really big project in. (However, I have done really big projects in
MATLAB and they’re a nightmare to debug).
- M.
On 28 March 2011 09:35, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
Hi Joel,
Why did you comment out mapZoom(e)?
Uncomment it and see.
I couldn’t get it to work well enough using CSS scaling to be usable.
I had a third idea which I ran out of time to try, which is to do
everything inside of SVG, where you’ve got (presumably) better-
supported scaling and rotation. Since SVG is part of the DOM, it
wouldn’t be much different from the code you’re looking at.–
J.
- The element test does not work in IE8 either. I can only see the top
left corner of whatever is being displayed “Axis Air Points”. see no
pieces, cannot scroll the map etc…too many different browser issues to deal with going this approach
I couldnt’ scroll it either, but I assumed that was because the scroll bars
had to be implemented specifically. I did see the pieces, however.
Thus spake Michael Kiefte:
I couldnt’ scroll it either, but I assumed that was because the scroll bars
had to be implemented specifically. I did see the pieces, however.
Did you try to drag on the map? That’s how scrolling was supposed to
work in the second demo. Were you able to drag the pieces?
–
J.
I was able to drag the pieces, but not scroll the map. I did try clicking
on the map.
On 30 March 2011 06:04, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
I couldnt’ scroll it either, but I assumed that was because the scroll
bars
had to be implemented specifically. I did see the pieces, however.Did you try to drag on the map? That’s how scrolling was supposed to
work in the second demo. Were you able to drag the pieces?–
J.
Thus spake Michael Kiefte:
I was able to drag the pieces, but not scroll the map. I did try clicking
on the map.
Clicking on the map, or dragging? Just clicking on the map won’t do
anything.
In what browser?
–
J.
I finished reading the Mozilla documentation on JavaScript, and inheritance
is a nightmare. Since there are not classes, inheritance is based on a
prototype instantiation. The syntax for inheritance is a gigantic kludge and
there appear to be several ways of doing it–none of which are necessarily
intuitive. I have a sudden urge to do everything in assembler. There are a
few other quirks that will make it bug prone – some of which I posted
above. I was against JavaScript before I started investigating it and now
I’m actually much more firm in my opposition. It’s a bad language.
On 29 March 2011 17:25, Michael Kiefte mkiefte@dal.ca wrote:
I just had to post this bit. You’re allowed to have an array of length 5
in which the myArray[3] is invalid following delete myArray[3]; Object
properties seem unmanageable and methods are implemented rather poorly (you
have to assign them like variables). JavaScript seems fine for small
projects where you’re the only developer, but for multi-developer projects,
it would be hard to coordinate. I really can’t imagine working with this for
anything complicated.From the docs:
At the implementation level, JavaScript’s arrays actually store their
elements as standard object properties, using the array index as the
property nameDidn’t sh used to work like this? I guess there’s a reason why it’s called
JavaScript.
- M.
On 29 March 2011 15:22, Michael Kiefte mkiefte@dal.ca wrote:
Some choice quotes regarding JavaScript on the Mozilla website that made
me cringe:JavaScript is a small, lightweight language; it is not useful as a
standalone language, but is designed for easy embedding in other products
and applications, such as web browsers.JavaScript is a very free-form language compared to Java. You do not have
to declare all variables, classes, and methods. You do not have to be
concerned with whether methods are public, private, or protected, and you do
not have to implement interfaces. Variables, parameters, and function return
types are not explicitly typed.In expressions involving numeric and string values with the + operator,
JavaScript converts numeric values to strings. For example, consider the
following statements:
1 x = “The answer is " + 42 // returns “The answer is 42”
2y = 42 + " is the answer” // returns “42 is the answer”In statements involving other operators, JavaScript does not convert
numeric values to strings. For example:
1 “37” - 7 // returns 30
2"37" + 7 // returns “377”Another unusual thing about variables in JavaScript is that you can refer
to a variable declared later, without getting an exception.If an array is created using a literal in a top-level script, JavaScript
interprets the array each time it evaluates the expression containing the
array literal. In addition, a literal used in a function is created each
time the function is called.That’s just the from first three pages. I’m actually going to learn
JavaScript anyway as I wouldn’t mind using it for some lectures (I use
pdfLaTeX + Beamer and you can embed JavaScript in the resulting PDF). But
it kind of reminds me of MATLAB or perl – not something that you’d want to
do a really big project in. (However, I have done really big projects in
MATLAB and they’re a nightmare to debug).
- M.
On 28 March 2011 09:35, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
Hi Joel,
Why did you comment out mapZoom(e)?
Uncomment it and see.
I couldn’t get it to work well enough using CSS scaling to be usable.
I had a third idea which I ran out of time to try, which is to do
everything inside of SVG, where you’ve got (presumably) better-
supported scaling and rotation. Since SVG is part of the DOM, it
wouldn’t be much different from the code you’re looking at.–
J.
No I tried that. I was on Firefox (not the latest I think) on a MacBook Pro
running Linux. The MagicMouse is a little wierd under Linux, but it works
for everything else (except there’s no middle button and there is no virtual
scroll wheel). I didn’t try it on anything else.
On 30 March 2011 06:10, Joel Uckelman uckelman@nomic.net wrote:
Thus spake Michael Kiefte:
I was able to drag the pieces, but not scroll the map. I did try
clicking
on the map.Clicking on the map, or dragging? Just clicking on the map won’t do
anything.In what browser?