Feels Like Ruby - Ruby Kaigi 2010

Feels Like Ruby
Sarah Mei
Pivotal Labs

@sarahmei
sarah@pivotallabs.com

1

すみませんーはじまりましょうか。

皆さん、こんにちは

Hi everybody

2

みんなさん、こんにちは。

メイサラ
名前は MEI Sarah です。

I’m Sarah Mei.

3

なまえは Mei Sarah です。はじめまして、どうぞうよろしくおねがいします。

日本語がよく話せないですから、
すみません。

I don’t speak Japanese very well, so
thanks in advance for your patience.

4

にほんごがよくはなせないですから、すみません。

http://www.ﬂickr.com/photos/sunrise/4064417/
5

San Franciscoにすんでいます。

アメリカ人です。 I’m American.

http://www.ﬂickr.com/photos/junewess/3756778580/
6

Americaじんです。

RubyとRailsの開発者です。

I’m a Ruby & Rails
developer.

Image copyright 2006-2010 Yukihiro Matsumoto
7

Ruby のかいはつしゃです。

I work at
ピヴォタルラブス

に勤めています。

8

Pivotal Labs につとめています。Pivotal Labs は Pivotal Tracker をせいさくしてい
ます。でも、ほとんどの Pivotal Labs のしゃいんはコンソルタンットです.

I work at
ピヴォタルラブス

に勤めています。

ピヴォタルトラッカー

8

Pivotal Labs につとめています。Pivotal Labs は Pivotal Tracker をせいさくしてい
ます。でも、ほとんどの Pivotal Labs のしゃいんはコンソルタンットです.

（この先から英語です。ごめんね）

9

じこしょうかいがおわりですから、このさきから英語です。ごめんねえ。。。


Feels Like Ruby

9



Feels Like Ruby
Making JavaScript a
Real Language

9


What I like about Ruby

10

I want to set the stage by talking about what I enjoy about Ruby. First and foremost, it’s the
language itself. I love the expressiveness and accessibility.

But as a working developer, what I appreciate the most is the ability to test-drive everything.
Between rspec, test::unit, cucumber, capybara, webrat, shoulda, steak....I can pick the most
appropriate test tools for each project.


• The language itself.

10




• The language itself.
• I can test-drive everything.

10




• The language itself. JavaScript

• I can test-drive everything. JavaScript

11

So let’s see how these options stack up in JavaScript. The language itself...?


• The language itself. X
JavaScript


12

Well, I’m never going to be able to change that. I don’t dislike JavaScript, but Ruby ﬁts my
personality better. But what about test-driving?


• The language itself. X
JavaScript

O

13

We should be able to test-drive JavaScript. But until earlier this year, I didn’t. And some of the
best Rails developers I know, who test-drive all their Ruby code, still don’t test-drive their
JavaScript. So the question is...

http://www.ﬂickr.com/photos/petereed/496392956
14

Why not? Why do we make JavaScript development so painful?

I think part of it is a philosophical mismatch in the way Rails treats JavaScript.

15

Web applications are fundamentally written in multiple languages. Here’s a very generic
representation of a Ruby web application. On the front end, there’s HTML, CSS, and
Javascript, and on the back end there is one (or more!) server languages, plus SQL. And of
course, normal applications have other front-end languages too, like ActionScript or
Objective-J, and other back-end languages interacting with Ruby, and usually additional data
stores as well. I can’t remember the last time I worked on an application that had ONLY a
relational database for storage.

But traditionally, in this setup, programming languages sit here in the middle. But
frameworks try to extend on either side. That’s what Rails does.

ActiveRecord

Rails

16

For example, Rails extends this direction, and abstracts away SQL with ActiveRecord. It’s
pretty successful with that. Even on really complex applications, I can get away with the
generated SQL most of the time.

erb
sass
rjs
ActiveRecord

Rails/gems Rails

17

But it also extends the way with erb and rjs to generate HTML and JavaScript. And with other
gems, you can generate CSS too. And although this was a good idea with SQL and
ActiveRecord, and it works decently well with HTML and CSS, RJS is kind of a disaster. I’ll show
you an example in moment.

But first I want to point out that this is not a failing of Rails, or of the people who wrote it.
This is the nature of Javascript. It might be the one language whose use is evolving even
faster than Ruby. SQL has an ISO standard and a committee, and if they make any significant
changes, we’ll have five years’ notice. Moreover, the database products that implement SQL
have committees, so as SQL end-users, we’re exceedingly well-insulated from any language
churn.

JavaScript Developers

http://www.ﬂickr.com/photos/gem66/387400306
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But Javascript...is the wild west. It’s the frontier. While the language itself is relatively stable,
its libraries and usage patterns are changing faster than that of Ruby, or of Rails, or of any
other framework.

What does that mean for us as web application developers, as multi-lingual programmers?

erb
sass
rjs
ActiveRecord

Rails/gems Rails

19

It means we need to opt-out, to make an exception, and to handle JavaScript differently.
Now, that’s the philosophical reason - now I want to show you the practical reason.

20

In Rails 2, using RJS means you have little bits of Javascript all over your code.

Here’s an example I adapted from the “complex forms” railscast. This is a to-do list app, in
which you can create a project with any number of tasks attached. This is the new project
form. It has 3 task textﬁelds, but you can add another one by clicking “Add a task”, and you
can delete one by clicking the “remove” link that’s next to it. Both of these are implemented
as simple JavaScript that modiﬁed the DOM. For the purposes of this example, we’re going to
focus on the remove link.

So let’s look at how that’s implemented.

21

This is the partial that is rendered for each task. The important part is the link_to_function,
where when we click remove, it calls that little piece of javascript.

22

Here’s what the rendered HTML looks like. You’ve got that little bit of inline javascript, which
on its own, is fairly simple. But it’s not really testable.

Sure, you could write a selenium test that tests that it actually removes the dom element.
However, Selenium is slow. This is one simple interaction - in a typical modern web
application, there’s likely to be dozens of these on one page, if not hundreds. Testing them
all with Selenium would mean you’d have a test suite that never stopped running.

Plus, Selenium is an integration test. If all you’re doing is integration tests, you’re doing it
wrong. You need both unit tests and integration tests to probe all the behavior of your code.

So how can we re-do this in a way that is testable and repeatable?

A different approach

23

1. Forget RJS - it gets in your way once you do anything beyond the very simple.
2. Put your JS in classes - of course JS is a prototype-based language instead of an
inheritance-based language, but you can still organize your functions into sets. I’ll show you
what that looks like in a moment.
3. Organize your JS by behavior, and by location.
4. Test-drive all your JS.


• Forget RJS - write functions

23



• Put your functions in classes

23



• Organize classes by behavior and
location

23



location

• Test-drive your classes.

23


Unobtrusive JavaScript

location

• Test-drive your classes.

24

These ﬁrst two techniques are collectively known as “unobtrusive JavaScript.” I am happy to
report that Rails 3 is moving to unobtrusive JavaScript. So Rails 3 will help this problem quite
a bit, but, as you can see, there is more to do beyond “unobtrusiveizing.” Let’s look at how
we’d do it.

25

Here’s our original example, with the remove link. How we could re-implement it? Before, the
code looked like this...

26

But we can simplify this now. All we really have here is a link that we want to add a behavior
to.

27

So in the erb template, we’ll just make a link with a class on it. No reference to JavaScript
anywhere here. And here is...

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...the HTML it generates. So. If we don’t put our Javascript in the HTML...where should we put
it?

public/javascripts !

29

In general, I keep my JavaScript ﬁles in public/javascripts. So we’ll create a ﬁle in public/
javascripts called project_form.js

project_form.js

30

In this ﬁle, we create a class called RubyKaigi.ProjectForm, and we put in two functions. The
two functions are initialize and remove_task.

project_form.js

31

In initialize, we add a click event to all links with class .remove-link. When that link is clicked,
our other function is called.

project_form.js

32

That function, remove_task, actually removes the element with class ‘task’ from the DOM.

project_form.js

33

The last thing that’s important here is the document.ready, which calls initialize, which sets
up the click events, once the page is loaded.

34

So I’ve created a JavaScript class that encapsulates the behavior of the project form. Once I
implement the “Add a task” link, that behavior will go in the same class.

35

Then it might look something like this, with a new function at the bottom, and some extra
initialization at the top.

Organizing by page
What if you use the ProjectForm JS on
more than one page?

36

Organizing by page
What if you use the ProjectForm JS on
more than one page?

Move ProjectForm.initialize to a page
class initializer

36

project_edit_page.js

38

project_new_page.js

39

http://www.ﬂickr.com/photos/uwehermann/132244826
40

So that’s how you organize your JavaScript so it’s all in one place. But what about testing?

Jasmine

@jasminebdd
41

That’s where Jasmine comes in. Jasmine is Pivotal’s open-source JavaScript testing
framework.

It lets you do “rspec-style” testing.

The philosophy of Jasmine is that JavaScript should be tested with JavaScript. There are gems
out there such as harmony that let you test JavaScript with Ruby, but that just adds another
layer of indirection. JavaScript should be a ﬁrst-class language in web applications.

Also, it is not dependent on the DOM, so it can be used to test other types of JavaScript, such
as for WebOS.

Jasmine
• Open-source JavaScript test
framework from Pivotal

@jasminebdd
41

framework.



as for WebOS.

Jasmine

• BDD in the style of rspec

@jasminebdd
41

framework.



as for WebOS.

Jasmine

• Philosophy:

@jasminebdd
41

framework.



as for WebOS.

Jasmine

• Philosophy:
• Test JavaScript with JavaScript

@jasminebdd
41

framework.



as for WebOS.

Jasmine

• Philosophy:
• Test JavaScript with JavaScript
• No DOM dependency
@jasminebdd
41

framework.



as for WebOS.

gem install jasmine

42

43

When you install jasmine, it comes with a rake task that creates a javascripts directory under
spec.

44

I create a new ﬁle called project_form_spec.js. In this ﬁle I describe the behavior of the
functions in the RubyKaigi.ProjectForm class. Here’s the spec for removeTask.

45

It starts with a “describe”, like rspec, and the describe contains an “it” block. Both the
describe and the it take a string describing the behavior you’re expecting.

Jasmine comes with a small set of matchers - here you see expect().toEqual(). You can also
write custom matchers, as in rspec.

46

It comes with a little server built in, that starts on port 8888 by default, where you can run
your specs in a browser.

To re-run them, just reload the page.

Jasmine also comes with a continuous integration task that runs the specs in a browser and
uses selenium to determine whether they pass or fail. There are plug-ins that run your specs
headlessly.

Summary

• Respect your JavaScript!
• Test-drive

47

http://www.ﬂickr.com/photos/zachklein/54389823
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http://www.ﬂickr.com/photos/rappensuncle/248625025
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Questions?
質問がありますか。
@jasminebdd

@sarahmei
sarah@pivotallabs.com

http://www.ﬂickr.com/photos/rappensuncle/248625025
50

じゃ、これはいじょうです。

Feels Like Ruby - Ruby Kaigi 2010

Feels Like Ruby - Ruby Kaigi 2010

Feels Like Ruby - Ruby Kaigi 2010

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