jqpm: Package Manager for jQuery

2012-07-07 15:05

There is a specific technology I wanted to play around with for some time now; it’s called node.js. It also happens that I think the best way to get to know new stuff is to create something small, but complete and functional. Note that by ‘functional’ I don’t really mean ‘practical’; that distinction is pretty important, given what I’m about to present here.

Basically, I wrote a package manager for jQuery. The idea was to have a straightforward way to install jQuery plugins – a way that somewhat mirrors the experience of dozens of other package managers, from pip to cabal. End result looks pretty decent, in my opinion:

  1. $ jqpm install flot
  2. [jqpm] flot installed successfully
  3. $ ls *.js
  4. jquery.flot.js

The funny part? It doesn’t use any central, remote registry of plugins. What it does is searching GitHub and pulling code directly from there – provided it is able to find something relevant that looks like jQuery plugin. That seems to work well for quite a few popular ones, which is rather surprising given how silly and simplistic the underlying algorithm is. Certainly, there’s plenty of room for improvement, including support for jquery.json manifests – the future standard for the upcoming official plugin site.

As I said before, though, the main purpose of jqpm was educational one. After toying with underlying technologies for a couple of evenings, I definitely have better perspective to evaluate their usefulness. While the topic might warrant a follow-up posts in the future, I think I can briefly summarize my findings in few bullet points:

  • Node’s JavaScript is almost the same language you can find in your browser, with all of its wats, warts and shortcomings. That’s not a big problem if you already learned to deal with them, but I surely wouldn’t recommend it as starter language for novices. Additionally, it also turns out to be quite verbose language, with all the ubiquitous functions and loops, and without denser syntactic sugar such as list comprehensions.
  • By contrast, the standard library of Node is very nice mixture of usefulness and minimalism. It’s certainly not as rich as Python’s or Java’s, but it’s more than usable, despite sitting a bit on the low level side.
  • The canonical tool for managing dependencies, npm, is rather curious creature. Combined with the way Node resolves require() calls, it makes for an unusual system that resembles classic C/C++ #includes – but improved, of course. What stands out the most is the lack of virtualenv/rvm-style utilities; instead, an equivalent approach of local node_modules subfolders is used instead. (npm faq and npm help folders provide more elaborate explanation on how does it work exactly).
  • The callback-based, asynchronous computation is a big hindrance that doesn’t really seem worthwhile. Intriguingly, the hassles of async vs. sync feel strangely similar to issues with pure vs. impure code in functional languages such as Haskell; in both cases you need some serious refactoring of brainware to start coding effectively. In Haskell, however, you are gaining tremendous boons to correctness, modularization, parallelization and testability. In Node, it’s disputable whether you actually gain anything: the whole idea of I/O based on a single event loop sounds all too similar to what an operating system already does with threads sleeping on I/O calls and hardware interrupts that wake them. Granted, this incarnation of asynchronous I/O is much better than some older ones, but that’s mostly thanks to JavaScript being much better equipped to handle the callback bonanza than plain ol’ C.

The bottom line: node.js is definitely not a cancer and has many legitimate uses, mostly pertaining to rapid transfer of relatively small pieces of data over the Internet. API backends, single page web applications or certain game servers all fall easily into this category.

From developer’s point of view, it’s also quite fun platform to code in, despite the asynchronous PITA mentioned above (which is partially alleviated by libraries like async.js or frameworks providing futures/promises). On the overall abstraction ladder, I think it can be placed noticeably lower than Java and not very much higher than plain C. That place is an interesting one, and it’s also not densely populated by any similar technologies and languages (only Go and Objective-C come to mind). Occupying this mostly overlooked niche could very well be one of reasons for Node’s recent popularity.

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Author: Xion, posted under Internet, Programming, Thoughts »


2 comments for post “jqpm: Package Manager for jQuery”.
  1. Kos:
    July 22nd, 2012 o 23:04

    What do you mean, without list comprehensions? :D

  2. Xion:
    July 23rd, 2012 o 14:15

    Basically, you need to spell out your loops explicitly. Or use stuff like forEach(), $.each(), _.map() with functions which are also verbose.

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