By Derek Santos – consultant

I’ve been experimenting with CoffeeScript lately and wanted to pass along some things I really like about it.

1. It writes very good JavaScript

CoffeeScript compiles to JavaScript that follows best practices and sticks to JavaScript’s good parts. For example:

• == always turns into ===
• Code automatically gets wrapped with a self calling function to protect its scope
• var declarations always get moved to the top

2. It’s readable

Whitespace is meaningful in CoffeeScript (which can be hard to get used to at first), but consider the following example:

JavaScript

if (devices !== null && devices !== undefined) {
    devices.push({
	name : 'iPhone 6',
	manufacturer : 'Apple'
    });
}

CoffeeScript

if devices?
    devices.push
	name : 'iPhone 6'
	manufacturer : 'Apple'

It’s a simple example, but you can see how CoffeeScript removes the unnecessary syntax and reads more like a sentence.

3. String Interpolation

This is one thing I will admit is tedious in JavaScript (and some other languages). We’ve all had to do this before.

html = '<div>';
html += '<h2>' + title + '</h2>';
html += '<p>' + body + '</p>';
html += '<span>' + footer + '</span>';
html += '</div>';

In CoffeeScript, this would be accomplished with:

html =
"""
<div>
	<h2>#{title}</h2>
	<p>#{body}</p>
	<span>#{footer}</span>
</div>
"""

A templating engine could be used to give the same result, but that also adds extra weight to your project. This is not so in CoffeeScript since it just gets compiled into pure JavaScript and makes it much cleaner.

4. Classes and Inheritance

If you are coming from a classical programming language such as Java, CoffeeScript allows you to structure your code in a way that is familiar to you. CoffeeScript also has some helpful nuggets like using => instead of -> to bind a particular scope to your functions.

5. It’s fantastic for writing unit tests

If you are reluctant to try CoffeeScript because you are afraid of how it will affect your project, I strongly urge you to try writing your unit tests in CoffeeScript. This way, you’ll be learning it in a risk-free environment while still providing value to your projects. You’ll find that your tests will be incredibly easy to read and author using CoffeeScript.

Here is a sample Jasmine test written in CoffeeScript:

describe 'controller', ->
    target = app.mycontroller

    it 'should call a service and return a response', ->
        target.makeRequest (result) ->
            expect(result).toBe('success!')