Shadowing variables in CoffeeScript

[ziz]

CoffeeScript is a meta-language which compiles directly into JavaScript, has some neat features and patterns baked in, and is a favorite of many JavaScript hackers, and I’ve been playing around with it in the last few days.

For the most part, I like it, but it steps on one of the most useful features of JavaScript - the var keyword for scope

Comments

[okterok]

I read "bat ticks" about 3 times before I got that you said "back ticks" >.< really need more sleep.

So why would a person use Coffee Script over JavaScript?

[ziz]

Well, it has a lot of nice features that javascript doesn't make easy, like list comprehensions, existence tests, conditional assignment, and so forth. My favorite feature is the much shorter syntax for function binding, which is extremely helpful when you're writing jquery. From this tumblr, for example -

CoffeeScript:

object =
func: -> $('#div').click => @element.css color: 'red'

compiles to JavaScript:

var object;
var __bind = function(fn, me){ return function(){ return fn.apply(me, arguments); }; };
object = {
func: function() {
return $('#div').click(__bind(function() {
return this.element.css({
color: 'red'
});
}, this));
}
};

Shorter and quicker to write, easier to scan, with much less boilerplate for doing the same constantly-repeated patterns in javascript.

[okterok]

Wow that's really slick! Do you have a tutorial url to share?

[ziz]

Sure - the reference is at coffeescript.org (and you can try it out online there, too), and another take on introducing the features is at tutsplus. A bunch of tutorials are linked at this blog, and on quick glance, it looks like there's some worthwhile ones there.