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To summarize: you make your way across the board by adjacent shape- and color-matching. The game is a competitive puzzle based around color- and shape-matching. By “little while” I mean three years, the majority of which was spent at a plateau where the game theoretically worked, but was too intense to use … until I thought of this approach. To illustrate, I’m going to look at a project I’ve been developing on the side for a little while.
#Javascript multibrowser lowerstring code#
What I’m talking about here is the code required to understand the rules of a game, which can then evaluate situations and tactics in order to try to beat you at that game. The code takes a while to complete, sure, but it runs successfully all the way to the end, without the UI freezing and without warnings about excessively slow scripting. Now let’s run it in again … and this time we receive completely different results. Var result2 = document.getElementById('result2') So let’s re-factor it and use an asynchronous timer for the outer loop: function test2() In Opera there is no such dialog – it just continues to run the code until it’s done – but the browser UI is similarly frozen until the task is complete.Ĭlearly we can’t run code like that in practice. Safari 3 and Internet Explorer 6 behave similarly in this respect, with a frozen UI and a threshold at which a warning dialog is produced. If we allow it to continue, after another 90 iterations Firefox produces the same dialog again. After about 90 iterations, Firefox produces an “unresponsive script” warning dialog. Now let’s run that code in Firefox (in this case, Firefox 3 on a 2GHz MacBook) … and as expected, the browser UI freezes while it’s running (making it impossible, for example, to press refresh and abandon the process). Var result1 = document.getElementById('result1') Let’s demonstrate the problem with a simple test case involving two levels of iteration the inner level is deliberately too intensive so we can create the race conditions, while the outer level is fairly short so that it simulates the main code.
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Locking up the browser is obviously not an option, so if this is to work at all, we must find a way of making it run without error. That process, on the surface so simple, could be so intensive that the whole browser freezes while it’s happening. But matchAll() itself is pretty intense, having – as it does – to parse and evaluate any CSS1 or CSS2 selector, then walk the entire DOM tree looking for matches and the extension does that for each individual selector, of which there may be several thousand. The essence of this is a set of evaluations using the matchAll() method from Dean Edwards‘ base2: for(var i=0 i 0) The core of that extension is the ability to test CSS selectors that apply to a page, to see if they’re actually being used. That’s the situation I found myself in when developing my Firefox extension, Dust-Me Selectors. That might be the best solution in a given case perhaps some processing in an application needs to be moved to the server-side, where it has more processing power to work with, generally, and a genuinely threaded execution environment (a web server).īut eventually you may find a situation where that’s just not an option – where JavaScript simply must be able to do something, or be damned. Sometimes there’s simply no way to avoid the intensity of a particular operation, short of not doing it in JavaScript at all. Normally, if I were writing a script that proved to be too intensive, I would look at re-engineering it such a significant slowdown usually indicates a problem with the code, or a deeper problem with the design of an application.īut sometimes it doesn’t.