Mad scribblings and inexpert musing

CoffeeScript: An Outsider Opinion

published: 3 Jul 2011 09:07:00PM

Thoughts on CoffeeScript from a server-side developer just getting started with frontend and JavaScript development.

Firstly, if you’re unfamiliar with CoffeeScript, I recommend reading elsewhere for a proper overview and introduction. The CoffeeScript homepage and the Introductory Chapter of The Litte CoffeeScript Book are good resources for that. If you’re really impatient CoffeeScript is in the author’s own words "JavaScript's less ostentatious kid brother." I've also heard it called "Javascript for Ruby and Python programmers" and "What Javascript should have been" by several of my peers. It also seems that it could've been called CilantroScript1 as it seems to have an instantly polarizing effect on people in online communities such as Reddit and the Ruby on Rails community.

So why did I start working with CoffeeScript? A number of reasons.

I am a backend developer and want to grow my frontend skills. 1. I’m starting to experiment with Node.js on the server. 2. Jeremy Ashkenas's talk at CodeConf on literate programming blew my mind. 3.I know Ruby, so I should enjoy a “Javascript for Rubyists”, right? 4. It is going to be a Ruby on Rails default soon so I might as well check it out now. 5. I like new and shiny things.

One of the quandries I faced when deciding to learn CoffeeScript was the fact that I don’t know JavaScript. I spent 6 months noodling with Ruby before picking up Rails and am still getting my feet wet with Python before taking Django for a spin. So why on Earth would someone with my MO pick up CoffeeScript without first becoming proficient with javascript? (Aside: I’m tired of the CamelCasing) The answer comes from the first sentence (topic sentence, for those still in Jr. High School) in the second paragraph of the coffeescript home page.

The golden rule of CoffeeScript is: “It’s just JavaScript”.

As it turns out that isn’t entirely true since coffeescript is a class based object oriented language and javascript is prototype based. This was actually a mark against coffeescript for me since part of my desire to learn javascript was to dally in prototype based OOP. (Luckily there’s still Io for that.) But for the most part Coffee really is just javascript.

EDIT: Jeremy Ashkenas has kindly clarified this point for me.

CoffeeScript is prototype based to the precise same extent that JavaScript is. The "class" keyword is just sugar for JavaScript’s constructor function + prototype chain combination. To mangle Shakespeare:

What’s in a name? That which we call a class by any other name would smell as sweet. Call it a prototype if you like — it’s the same thing in code.

Thanks Jeremy, apologies for misapprehending.

So why the bother?

A while back I invested some of my hard-earned and short-in-supply cash to pick up a ten-pack of PeepCode tokens. I have to say, I've derived an intense amount of value from PeepCode but more on that later. I started with PeepCode's Meet CoffeeScript, had they produced a Meet JavaScript I would have started there, but they didn't. It took around six hours to watch the three and a half hour video. Almost immediately after, I started PeepCode’s Meet Node.js screencast and attempted to do it in javascript for about eight minutes. The appeal of coffeescript was immediately clear.

In JavaScript, I have to worry about whether or not every line ends in a semicolon, that there are no extraneous commas, yet commas where necessary, and that I've remembered the var keyword on all my local variables. All that stuff is important in JavaScript it doesn't actually effect my application in any way. In CoffeeScript, I can focus on the behavior of my code rather than the presentation of it. Instead of scrutinizing each line for a semicolon and each block for matching curly braces. I'm affirming that all my variables are scoped properly and that my code does what I want it to do. It doesn't add much to javascript but rather, reduces the amount of worry and focus on what is at the end of the day arbitrary stuff.

Sure, I have Vim configured with the fantastic Synastic plugin and I get notified when I drop a semicolon or have an unmatched brace but what's the point? Basic sanity checking is all it can really do. Why even waste the time to go back and insert those in the first place?


I’m still continuing my education in JavaScript, CoffeeScript, jQuery, Node.js, and prototype-based OOP. I'm armed with the beta copy of the CoffeeScript book by Trevor Burnham from Pragmatic Programmers. I fully intend to use CoffeeScript for all of my development in Javascript environments, server- and client-side, work and play, for the foreseeable future.

My CoffeeScript Resources

  1. The CoffeeScript Website and Documentation
  2. Meet CoffeeScript
  3. CoffeeScript: Accelerated JavaScript Development by Trevor Burnham
  4. The Annotated CoffeeScript Source
  5. The Little CoffeeScript Book
  6. Javascript: The Good Parts by Douglas Crockford
  7. Eloquent Javascript by Marjin Haverbeke
  8. Smooth CoffeeScript by autotelicum via @Raynos2

  1. Cilantro (or Coriander) is an herb which to some people tastes pleasantly citrus-like and to others is rank and revolting or soapy. As a result many people either love it or hate it. Few are ambivalent about Cilantro. The same is true of CoffeeScript in my observation.