Javascript vs CoffeeScript

Recently, we had a big debate about the usefulness of CoffeeScript vs keeping on with Javascript only. We also had a fit over Backbone, but I’ll leave that discussion for another day.

It came down to one major thing: people were stressed out about using Coffeescript any further because our deadline was fast-approaching and people didn’t want to learn more things along the way.

I think anyone could sympathize with the fact that learning new technologies can be an impediment to development. But it made me wonder–is CoffeeScript hard enough to learn that it’s an impediment to a furious development schedule? Or is it just that new technologies should never be introduced during such a time?

Well, here are a couple things about CofeeScript that might make a veteran Javascripter scratch their head at first:

Functions

They’re really nice once you get to know them. I appreciate the terse syntax, but it can be very confusing to look at for a long-time Javascript dev.

(arg1, arg2) ->
  alert 'inside a function'
# or
(arg1, arg2) -> alert 'inside another function'

class MyClass
  myFunc: (arg1, arg2) =>
    alert 'always bound to the "this" of any given instance of MyClass, because of the fat arrow ("=>")'

Classes

Not all Javascript devs will love the way CoffeeScript uses prototypical inheritance in its generated classes. Thankfully, CoffeeScript compiles to Javascript, so you can roll your own non-prototype-oriented classes as well.

MyClass = (constructorArg1, constructorArg2) ->
  # do stuff
  instanceMethod = ->
    alert 'a different type of js class'

  {
    exposedInstanceMethod: instanceMethod
  }

Array and Object Comprehensions

This is one thing that I love about CoffeeScript, actually. Then again, it’s something that is quite a bit different than Javascript.

list = [1, 2, 3]

# The following are equivalent:

for item in list
  doSomething(item)

doSomething(item) for item in list

# Also, you can treat array comprehenions as arrays themselves

x = (item + 1 for item in list)
x == [2, 3, 4] # => true

Hmm

Well, not much more to say, really. That’s not an exhaustive list of oddities, so staunch Javascript devs probably won’t be happy switching in a hurry. Is there a compromise?