Posts Tagged ‘class’

JavaScript classes

Thursday, May 5th, 2011

OK, think of it as a religious flamewar to the likes of "tabs vs. spaces for indentation". Looks like this particular war is currently (at JSConf and NodeConf) even more heated than it should be. Classes vs prototypes. For or against classes.

I personally don't care about the "winner". The thing is that classes currently don't exist in JavaScript. No such thing. However looks like they might in the next iterations of the language (see latest post from Brendan Eich). Some people miss classes so much that they start calling other things classes or come up with some approximation. Problem is, because classes don't exist, people often mean different things when they say "class".

Sometimes they mean "constructor functions". Sometimes they mean a regular object literal (singleton-type thing. Heck, "singleton" is also open for interpretations). Sometimes they mean an object or a function defined using Crockford's module pattern.

Sometimes it's some completely different home-grown (or library-provided) thingie called klass for example (in my "JavaScript Patterns" book I have one example for educational/thought-provoking purposes). It has to be klass, or _class or something weird. Because class is a reserved word. Unused, but reserved. And one day may be full of meaning. See the problem?

I avoid saying "class". It just doesn't exist. Imagine two months down the road ECMAScript comes up with classes. And they will most certainly not be the classes you may mean today (e.g. classes won't be another name for constructor functions, I'm sure).

So any written text/blog/documentation you've produced will become incorrect and even worse - misleading and confusing.

To summarize:

  • saying "class" today is confusing and takes extra effort to process (what do you mean? what was that again? it doesn't really exist and is not defined in the language, so an extra translation step is required)
  • saying "class" today will read plain wrong tomorrow, will confuse and misinform

Heck, even I have this "how to define a JavaScript class" post on my other blog. I wrote it years ago when, coming from PHP, I was curious how stuff works in JavaScript. Well I got it wrong then. But fixed it not too long ago because it was top 1 result in google and Yahoo search for "javascript class" and "javascript classes" and I didn't want to continue contributing to the confusion.

Note 2:
To my regret, I couldn't make it to JSConf (aka the best!) nor NodeConf this year (because all girls and women in my life are born in May and it's impossible to travel) so I may be a little off on the level of flamewarfare, but according to Twitter I'm not.