Monday, April 5, 2010

Day 59

Java Script!! So I finished my unbeatable TicTacToe last night... or this morning really. For only having 4 days (2 of which I was still quite sick) to learn a new language (2 really, since I didn't know HTML very well at all either), to learn and customize a new testing framework, and to create a new TicTacToe program, ai, and interface, it turned out really awesome. The interface was a little spartan, but it was fully functional with bonus features.

Though this was probably just because of the tools I was using, I found that I had to be exceedingly careful with Java Script. There are a lot of little things you can do or forget to do that will really mess you up. Since the code is all compiled in the browser, and most things in the language are done at run time, the errors can be pretty tough to chase. Even when using a testing framework like JsUnit, you just don't get very much valuable feedback from error messages.

As a result, I worked extremely carefully, doing everything slowly and very incrementally. I never made a huge changes without running my tests again and again, and making sure everything still worked along the way. This way, most of the errors I had were found within just a few moment by scanning through the recently changed code. I was also fortunate enough to have all the basic rules of what to do and what not to do fresh in my mind from the Java Script: The Good Parts book.

Another thing that I did, that I know saved me in a huge number of cases, is I would very, very frequently stop moving forward and move back two steps. Rather than adding another test and getting a new feature done, I would look back at what I had and see if I could find any better implementations. At first I did this just to try to make use of some of the cool benefits of the Prototypal and Functional nature of JavaScript, but after awhile it just didn't make sense not to go back and refactor. I found time and time again that if I hadn't turned back to refactor when I did, if I had just delayed it for one or two more features, I would have been stuck with a mess. At that point, I probably would have just kept what I had and continued to develop a messier and messier program.

It was also really easy. It just seemed like Java Script is the type of language that wants to be refactored. Perhaps its because I wasn't used to it. But it is also possible, because the language is so straight forward, so direct, and so expressive, that there is almost always a obvious and significant improvement that you can make.

Testing JS was a bit of a pain at first. Actually, it was a bit of a pain most of the time. Once again, this may be from my lack of experience, but JS and HTML seemed so intertwined that decoupling the logic from the GUI was often a challenge.

For example, to include a JavaScript file from another JavaScript file you have to actually generate some HTML to include it! I didn't want to explicitly write out
<script type="text/javascript" src="another.js"></script>
right in my first JS file, so instead I added another function to the document object which creates a script element, and plugs in the file you want. This way, anytime I wanted to include another .js file, I could call that function in my current .js file, and avoid having to write out the script line (which btw is fickle way to do it because certain browsers (like IE7) will read your <> ... < / script > as the tag for the previous include, and thus will mess everything up. So you actually would have to do <> ... < / scr + ipt > so that the tags couldn't be read until they were concatenated by the parser, and thus safe).

Here is how I did it:
document.addAnotherJavaScriptFile = function (filePath) {
var head = document.getElementsByTagName("head")[0];
var newScript = document.createElement('script');
newScript.setAttribute('type', 'text/javascript');
newScript.setAttribute('src', filePath);


This made it easy to include more files, if need be, and was a guaranteed way to work across browsers.

I am completely exhausted now and am gonna go pass out. Something I discovered last night/morning - when you are at the point where your brain shuts off (maybe around 2:30 - 3 AM) but you still have to get things done... it might honestly help more to just start trying random things and use guess and check rather than thinking it through. After I spent about 45 -60 minutes trying to work through a problem step by step, with no success, I decided to just start switching the important variables in a nearly random manner with the key values, and within about 3 minutes I stumbled upon the solution. Of course in the morning I spotted in almost immediately, but desperate times often require desperate measures. And hot damn, it got the job done.

Tomorrow I will go over some of the ways I used JsUnit to test my code. I will also be handing in my 8thLight Blog submission tomorrow, so that should be interesting.

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