Presented on 8/9/2011 to the Boston Ruby User's Group, this presentation talks about certain aspects of CoffeeScript and how it relates to Ruby.

1. CoffeeScript
A Rubyist’s Love Affair

2. Mark Bates
Ruby/Rails
Consultant
Author of
“Distributed
Programming with
Ruby”

3. “Insert Book Name
Here”

4. What CoffeeScript is
not!

5. No Just “Lack of
Punctuation!

6. NOT RJS!!!

7. RJS Example
page.replace_html('tasks-completed',
Task.completed_count)
page.replace_html('tasks-remaining',
Task.remaining_count)
page.replace_html('task-status-' + @task.id.to_s,
@task.status.description)
page.visual_effect(:highlight, 'task-item-' +
@task.id.to_s, :duration => 1.0)

8. So what is
CoffeeScript?

9. CoffeeScript is...
“a little language that compiles into
JavaScript”
Easier to read and write
A hybrid of Ruby and Python
Helpful

10. So why should I
embrace (and love)
CoffeeScript?

11. String Interpolation
name = 'Mark'
"Hello #{name}"

12. var name;
name = 'Mark';
"Hello " + name;

13. Heredoc
html = """
<div class="comment" id="tweet-#{tweet.id_str}">
<hr>
<div class='tweet'>
<span class="imgr"><img
src="#{tweet.profile_image_url}"></span>
<span class="txtr">
<h5><a href="http://twitter.com/#{tweet.from_user}"
target="_blank">@#{tweet.from_user}</a></h5>
<p>#{tweet.text}</p>
<p class="comment-posted-on">#{tweet.created_at}</p>
</span>
</div>
</div>
"""

14. var html;
html = "<div class="comment" id="tweet-"
+ tweet.id_str + "">n <hr>n <div
class='tweet'>n <span class="imgr
"><img src="" + tweet.profile_image_url +
""></span>n <span class="txtr">n
<h5><a href="http://twitter.com/" +
tweet.from_user + "" target="_blank">@"
+ tweet.from_user + "</a></h5>n <p>"
+ tweet.text + "</p>n <p class=
"comment-posted-on">" + tweet.created_at
+ "</p>n </span>n </div>n</div>";

15. Ranges
# 1, 2, 3, 4, 5
[1..5]
# 1,..., 4
[1...5]
#1,...,500
[1..500]
#5, 4, 3, 2, 1
[5..1]
#500,...,1
[500..1]

16. var _i, _j, _results, _results2;
[1, 2, 3, 4, 5];
[1, 2, 3, 4];
(function() {
_results = [];
for (_i = 1; _i <= 500; _i++)
{ _results.push(_i); }
return _results;
}).apply(this, arguments);
[5, 4, 3, 2, 1];
(function() {
_results2 = [];
for (_j = 500; _j >= 1; _j--)
{ _results2.push(_j); }
return _results2;
}).apply(this, arguments);

17. Ruby Style
Conditionals
Unless
In-line Conditionals

18. Conditionals
unless a
console.log "a is false"
console.log "a is false" unless a

19. if (!a) {
console.log("a is false");
}
if (!a) {
console.log("a is false");
}

20. Functions
Bound Functions
Default Arguments
Splatted Arguments

21. Regular Functions
p = (name)->
console.log "hello: #{name}"
p 'mark'

22. var p;
p = function(name) {
return console.log("hello: " + name);
};
p('mark');

23. Regular Functions
p = (name)->
console.log "hello: #{name}"
p 'mark'

24. Regular Functions
p = (name)->
console.log "hello: #{name}"
CoffeeScript
p 'mark'
p = ->(name) {
puts "hello: #{name}"
}
Ruby 1.9
p.call 'mark'

25. Bound Functions
class Person
def initialize(name)
@name = name
end
def bind
binding
end
end
p = Person.new('mark')
eval "puts @name", p.bind

26. Bound Functions
fetchData: =>
url = "http://search.twitter.com/search.json?
q=#{encodeURIComponent(@hash_tag)}&rpp=#{@max_results}&callba
ck=?"
$.get url, {}, @handleData, 'json'
handleData: (data) =>
if data['error']?
@handleError()
if data.results.length is 0 and @fall_back
@handleEmptyData()
else if data.results.length > 0
setTimeout (=> @fetchData()), 10000
@render data

27. var __bind = function(fn, me){ return function(){ return fn.apply(me,
arguments); }; };
({
fetchData: __bind(function() {
var url;
url = "http://search.twitter.com/search.json?q=" +
(encodeURIComponent(this.hash_tag)) + "&rpp=" + this.max_results + "&callback=?";
return $.get(url, {}, this.handleData, 'json');
}, this),
handleData: __bind(function(data) {
if (data['error'] != null) {
this.handleError();
}
if (data.results.length === 0 && this.fall_back) {
return this.handleEmptyData();
} else if (data.results.length > 0) {
setTimeout((__bind(function() {
return this.fetchData();
}, this)), 10000);
return this.render(data);
}
}, this)
});

28. Default Arguments
createElement: (name, attributes = {}) ->
obj = document.createElement name
for key, val of attributes
obj.setAttribute key, val
obj

29. ({
createElement: function(name, attributes) {
var key, obj, val;
if (attributes == null) {
attributes = {};
}
obj = document.createElement(name);
for (key in attributes) {
val = attributes[key];
obj.setAttribute(key, val);
}
return obj;
}
});

30. Splatted Arguments
splatter = (first, second, others...) ->
console.log "First: #{first}"
console.log "Second: #{second}"
console.log "Others: #{others.join(', ')}"
splatter [1..5]...

31. var splatter;
var __slice = Array.prototype.slice;
splatter = function() {
var first, others, second;
first = arguments[0], second = arguments[1], others = 3 <=
arguments.length ? __slice.call(arguments, 2) : [];
console.log("First: " + first);
console.log("Second: " + second);
return console.log("Others: " + (others.join(', ')));
};
splatter.apply(null, [1, 2, 3, 4, 5]);

32. Array Loop
arr = [1..5]
for num in arr
console.log num

33. var arr, num, _i, _len;
arr = [1, 2, 3, 4, 5];
for (_i = 0, _len = arr.length; _i < _len; _i++) {
num = arr[_i];
console.log(num);
}

34. Hash Loop
for key, val of attributes
console.log "key: #{key}"
console.log "val: #{val}"

35. var key, val;
for (key in attributes) {
val = attributes[key];
console.log("key: " + key);
console.log("val: " + val);
}

36. Classes
Easy To Define
Easy To Extend
Keep Code Clean

37. Classes
class Employee
constructor: (@name, @options = {})->
job: ->
@options.job
mark = new Employee('Mark', job: 'Developer')
mark.job() # => 'Developer'
mark.name # => 'Mark'

38. var Employee, mark;
Employee = (function() {
function Employee(name, options) {
this.name = name;
this.options = options != null ? options : {};
}
Employee.prototype.job = function() {
return this.options.job;
};
return Employee;
})();
mark = new Employee('Mark', {
job: 'Developer'
});
mark.job();
mark.name;

39. Extending Classes
class Manager extends Employee
job: ->
"$$$ #{super}"
steve = new Manager('Steve', job: 'CEO')
steve.job() # => '$$$ CEO'
steve.name # => 'Steve'

40. var Manager, steve;
var __hasProp = Object.prototype.hasOwnProperty, __extends = function(child, parent) {
for (var key in parent) { if (__hasProp.call(parent, key)) child[key] = parent[key]; }
function ctor() { this.constructor = child; }
ctor.prototype = parent.prototype;
child.prototype = new ctor;
child.__super__ = parent.prototype;
return child;
};
Manager = (function() {
__extends(Manager, Employee);
function Manager() {
Manager.__super__.constructor.apply(this, arguments);
}
Manager.prototype.job = function() {
return "$$$ " + Manager.__super__.job.apply(this, arguments);
};
return Manager;
})();
steve = new Manager('Steve', {
job: 'CEO'
});
steve.job();
steve.name;

41. @
class User
constructor: (@name)->
@new_record = true
@find: (id)->
# do some work

42. @
class User
constructor: (name)->
@name = name
@new_record = true
@find: (id)->
# do some work

43. var User;
User = (function() {
function User(name) {
this.name = name;
this.new_record = true;
}
User.find = function(id) {};
return User;
})();

44. Thank You
@markbates
http://www.markbates.com