Aaron Gustafson recently wrote a very interesting monograph bemoaning a recent trend to view JavaScript as “a virtual machine in the browser”. I’ll quote fairly extensively, because Aaron makes some really strong points here, and I have a lot of sympathy with them. But at bottom I think he’s wrong, or at the very least he’s looking at this question from the wrong direction, like trying to divine the purpose of the Taj Mahal by looking at it from underneath.
“The one problem I’ve seen,” says Aaron, “is the fundamental disconnect many of these developers [who began taking JavaScript seriously after Ajax became popular] seem to have with the way deploying code on the Web works. In traditional software development, we have some say in the execution environment. On the Web, we don’t.” He goes on to explain: “If we’re writing server-side software in Python or Rails or even PHP, … we control the server environment [or] we have knowledge of it and can author… accordingly”, and “in the more traditional installed software world, we can similarly control the environment by placing certain restrictions on what operating systems our code can run on”.
I believe that this criticism, while essentially valid, misapprehends the real case here. It underestimates the universality of JavaScript implementations, it overestimates the stability of old-fashioned software development, and most importantly it starts from the presumption that building things for one particular computer is actually a good idea. Which it isn’t.
Now, nobody is arguing that the web environment is occasionally challengingly different across browsers and devices. But a lot of it isn’t. No browser ships with a JavaScript implementation in which 1 and 1 add to make 3, or in which Arrays don’t have a length property, or in which the for keyword doesn’t exist. If we ignore some of the Mozilla-specific stuff which is becoming ES6 (things such as array comprehensions, which nobody is actually using in actual live code out there in the universe), JavaScript is pretty stable and pretty unchanging across all its implementations. Of course, what we’re really talking about here is the DOM model, not JavaScript-the-language, and to claim that “JavaScript can be the virtual machine” and then say “aha I didn’t mean the DOM” is sophistry on a par with a child asking “can I not not not not not have an ice-cream?”. But the DOM model is pretty stable too, let’s be honest. In things I build, certainly I find myself in murky depths occasionally with JavaScript across different browsers and devices, but those depths are as the sparkling waters of Lake Treviso by comparison with CSS across different browsers. In fact, when CSS proves problematic across browsers, JavaScript is the bandage used to fix it and provide a consistent experience — your keyframed CSS animation might be unreliable, but jQuery plugins work everywhere. JavaScript is the glue that binds the other bits together.
Equally, I am not at all sold that “we have knowledge of [the server environment] and can author your program accordingly so it will execute as anticipated” when doing server development. Or, at least, that’s possible, but nobody does. If you doubt this, I invite you to go file a bug on any server-side app you like and say “this thing doesn’t work right for me” and then add at the bottom “oh, and I’m running FreeBSD, not Ubuntu”. The response will occasionally be “oh really? we had better get that fixed then!” but is much more likely to be “we don’t support that. Use Ubuntu and this git repository.” Now, that’s a valid approach — we only support this specific known configuration! — but importantly, on the web Aaron sees requiring a specific browser/OS combination as an impractical impossibility and the wrong thing to do, whereas doing this on the server is positively virtuous. I believe that this is no virtue. Dismissing claims of failure with “well, you should be using the environment I demand” is just as large a sin on the server or the desktop as it is in the browser. You, the web developer, can’t require that I use your choice of browser, but equally you, the server developer, shouldn’t require that I use your particular exact combination of server packages either. Why do client users deserve more respect than server users? If a developer using your server software should be compelled to go and get a different server, how’s that different from asking someone to install a different web browser? Sure, I’m not expecting someone who built a server app running on Linux to necessarily also make it run on Windows (although wise developers will do so), but then I’m not really expecting someone who’s built a 3d game with WebGL to make the experience meaningful for someone browsing with Lynx, either.
Perhaps though you differ there, gentle reader. That the web is the web, and one should have a meaningful experience (although importantly not necessarily the same meaningful experience) which ever class of browser and device and capability one uses to get at the web. That is a very good point, one with which I have a reasonable amount of sympathy, and it leads me on to the final part of the argument.
It is this. Web developers are actually better than non-web developers. And Aaron explains precisely why. It is because to build a great web app is precisely to build a thing which can be meaningfully experienced by people on any class of browser and device and capability. The absolute tip-top very best “native” app can only be enjoyed by those to whom it is native. “Native apps” are poetry: undeniably beautiful when done well, but useless if you don’t speak the language. A great web app, on the other hand, is a painting: beautiful to experience and available to everybody. The Web has trained its developers to attempt to build something that is fundamentally egalitarian, fundamentally available to everyone. That’s why the Web’s good. The old software model, of something which only works in one place, isn’t the baseline against which the Web should be judged; it’s something that’s been surpassed. Software development is easiest if it only has to work on your own machine, but that doesn’t mean that that’s all we should aim for. We’re all still collaboratively working out exactly how to build apps this way. Do we always succeed? No. But by any measure the Web is the largest, most widely deployed, most popular and most ubiquitous computing platform the world has ever known. And its programming language is JavaScript.