I have no idea why you would want to use it, but because I have this selector extension and nowhere to put it, here it is:

jQuery.expr[':'].target = function ( a, h ) {
  return (a.id && (h = document.location.hash) && h === '#' + a.id)
};

Updated 6. aug. 2009: Optimized by @maranomynet

So I found my old Sokoban game. Originally a Windows application, I though it could be fun to try to remake it in JavaScript. So that’s what I did.

I wrote the bulk of it in about an evening, and spent a few more evenings applying spit and polish until I was satisfied that it worked the way I wanted. The whole thing is about 300 lines of mostly uncommented code running on top of jQuery — well, actually as a jQuery plugin.

The interresting bits

There are a few characteristics that make this implementation interesting. The first is that the game uses progressive enhancement methodology. The script runs through marked items on the webpage and makes valid Sokoban levels playable. If you don’t have JavaScript you can still read the level codes, which are normally written in a standard like this:

####
# .#
#  ###
#*@  #
#  $ #
#  ###
####

The @ is the worker, # are walls, . are docks, $ are boxes, and so on…

The symbols are image-replaced with CSS when the level is live, but the whole thing works without CSS. You can disable the styles if you desire to play the levels in pure ASCII.

This also means that the game is printable. At any moment in gameplay you can grab a hardcopy of your status and frame it. I am hard pressed to think of other printable games. Copying the level onto the clipboard also works just as it would any other text. Not really useful features for a game, but interesting side-effects nonetheless.

Because parsing all the levels immediately as the game loads up — especially on level collections that have very many levels — is quite labour intensive, I am applying a recent jQuery plugin of mine, .processEach(), to prevent the browser from locking up. In short, it works like .each() but yields the process every iteration to allow the browser some time to do other things. It’s perhaps a subject of another entry.

Have fun

Have fun with the game and the source (which are released under the GPL v3). I suspect that it might one day be exactly what a Sokoban level blog is looking for, but for now it mostly remains a curiosity rather than a spectacular reproduction of the game,

The great thing about PHP is that it is present in some form on nearly all servers. If you’re careful to avoid version 5 features then you can pretty much expect your code to run wherever.

For a recent prototype I needed JSON (which wasn’t introduced to PHP until version 5) on a 4.3 system. Being a relentless do-it-yourself’er I have written a tiny JSON functionality “library” for older versions of PHP.

It’s about 5k of mostly comments. Available under MIT licence from Google code. Have fun.

Given a cell in a HTML table, what is it’s column index?

This seems like it’s simple. You just count the cells preceding it. Fine. Works for 99% of cases. But what if the table looks like this?:

Suddenly things are very complicated again. The last row really only contains two cells and the browser reports cell indexes 0 and 1 on those, respectively. Not the 3 and 4 I was hoping for.

My first thought was simply adding up the number of cells preceding this one which had a greater row index + row span than the row index of my subject cell. This doesn’t work because of cells like #4 & #13.

Eventually I simply ended up with a brute force method that does the job. But is unfortunately neither fast nor elegant. But then, what code of mine is?

It’s presented here in case anyone else needs to solve the same annoying problem. Or if anyone can suggest a nicer (or preferably a faster) method of doing this.

View demo and code.

My idea is that if we have a process that would benefit from extending Object.prototype, then we can do this during the time we are processing. Afterwards we simply remove the extensions and everything is back to normal.

Object.prototype.toHTML = htmlGenerationFunction;
myObject.toHTML();
delete Object.prototype.toHTML;

This trick won’t work on browsers that don’t implement the delete operator (IE3), and it’s going to be a pain if hasOwnProperty isn’t supported either (Safari 1 and IE5.0). But if you’re not supporting those browsers then you can consider this trick (test yours here).

I’ve thrown together a toJSON converter using this method. Admittedly, the code is no cleaner than the original example, but it works, will use native methods where available, and proves the concept.