CoffeeScript is a language that compiles to JavaScript. It simplifies JavaScript syntax by removing semicolons and curly braces, using indentation to define code blocks instead. CoffeeScript provides syntactic sugar that generates cleaner JavaScript code. Variables are private by default and functions return the last statement. CoffeeScript uses operators like 'is' and 'isnt' instead of '==' and '!=' and loops through arrays and objects differently than JavaScript.

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