This is just a quick introduction of CoffeeScript for people to get started

1. Getting Started
with
Akshay Mathur

2. CoffeeScript
• A language with simple syntax
– No semicolons and braces
– Resembles to English
– Indentation decides the code blocks
• Compiles into Javascript
– Provides syntactic sugar for boilerplate code
• Manage variable scope
• Class instead of prototype
– Generates good quality, error free code
@akshaymathu 2

3. Insallation
• Install Node JS and Package Manager (npm)
– See http://nodejs.org/download/ for details
• Install CoffeeScript
– See http://coffeescript.org/ for details
sudo npm install -g coffee-
script

4. Coffee to JS
• Compile a .coffee file into .js file using coffee
compiler
coffee -c myfile.coffee
Creates myfile.js
– See http://coffeescript.org/ for more options and
examples

5. Cofeescript to Javascript
greet_me = (name) ->
greeting_word = 'Hello!'
alert "#{greeting_word} #{name}”
Compiles to
greet_me = function(name) {
var greeting_word;
greeting_word = 'Hello!';
return alert("" + greeting_word
+ " " + name);
};
@akshaymathu 5

6. Variable Scoping
• Defines all variables in the first line of the
function
– This all variables become private by default
• Adds an anonymous wrapper function at the
top
– Even global remains within the closure
– If you want to make something available outside,
attach it to an object outside (e.g. window object)
@akshaymathu 6

7. Functions
• No ‘function’ keyword
– Use -> instead
• No curly braces {}
– Indent the code instead
• Last statement always returns
• No parenthesis while calling the function if
argument is being passed
• Default values can be used in function
signature
@akshaymathu 7

8. Function Examples
Fn = ->
Add = (x, y=0) ->
x + y
Add 3
var Fn, Add;
Fn = function(){};
Add = function(x, y)
{
if ( y == null){
y = 0;
}
return x + y;
};
Add(3);
@akshaymathu 8

9. Conditional Statements
mood = Improved if singing
if happy and knowsIt
clapsHands()
chaChaCha()
else
showIt()
date = if friday then sue
else jill
var date, mood;
if (singing) {
mood = Improved;
}
if (happy && knowsIt) {
clapsHands();
chaChaCha();
} else {
showIt();
}
date = friday ? sue : jill;
@akshaymathu 9

10. Looping on Arrays using ‘in’
foods = [
'broccoli’
'spinach’
'chocolate’
]
eat food for food in
foods when food isnt
'chocolate'
foods = ['broccoli',
'spinach',
'chocolate'];
for (_k = 0, _len2 =
foods.length; _k <
_len2; _k++) {
food = foods[_k];
if (food !==
'chocolate') {
eat(food);
}
}
@akshaymathu 10

11. Looping on Objects using ‘of’
yearsOld =
max: 10
ida: 9
tim: 11
ages = for child, age of yearsOld
"#{child} is #{age}"
var age, ages, child, yearsOld;
yearsOld = {
max: 10,
ida: 9,
tim: 11
};
ages = (function() {
var _results;
_results = [];
for (child in yearsOld) {
age = yearsOld[child];
_results.push(
"" + child + " is " + age
);
}
return _results;
})();
@akshaymathu 11

12. Operators
is ===
isnt !==
not !
and &&
or ||
true, yes, on true
false, no, off false
@, this this
of in
in No JS equivalent
@akshaymathu 12

13. Thanks
@akshaymathu 13