Javascript_include_tag and custom js files

Rails
1

The default setting in my application.html.erb is:

<%= stylesheet_link_tag ‘application’, media: ‘all’,
‘data-turbolinks-track’: ‘true’ %><%= javascript_include_tag
‘application’, ‘data-turbolinks-track’: ‘true’ %>

I have a cusom.css.scss file in app/assets/stylesheets which is included
as
part of the application.css file included in the site layout, supposedly
because of the

stylesheet_link_tag ‘application’ line of code.

I therefore planned to put all the javascript (jQuery and bootstrap) for
my
application in custom.js inside app/assets/javascript.
Would rails automatically load this file or am I expected to explicitly
tell rails to load it?

What confuses me is that in the Ruby on Rails tutorial, when jQuery is
used, it is put inside the html.erb document, like in Chapter 13
https://www.railstutorial.org/book/user_microposts#code-jquery_file_test,
so that on the one hand it is used a custom.css.scss file as stylesheet,
on
the other hand, when javascript is required, it is inserted inside the
html.erb document.

2

On Sun, Jul 10, 2016 at 5:43 AM, ‘krfg’ via Ruby on Rails: Talk
[email protected] wrote:

I therefore planned to put all the javascript (jQuery and bootstrap) for my
application in custom.js inside app/assets/javascript.
Would rails automatically load this file or am I expected to explicitly tell
rails to load it?

What do the comments in

app/assets/javascripts/application.js

say about that?

–
Hassan S. ------------------------ [email protected]

twitter: @hassan
Consulting Availability : Silicon Valley or remote

3

I past and copy below the content of my application.js file.
The lines ‘//= require jquery’ and ‘//= require jquery_ujs’ should
assure
that the jquery and jquery-ujs files provided by jquery-rails gem will
be
added to the asset pipeline and available for use. “The require_tree
directive tells Sprockets to recursively include all JavaScript files
in
the specified directory into the output. These paths must be specified
relative to the manifest file”.(quoted from guides.rubyonrails.org
http://guides.rubyonrails.org/asset_pipeline.html#manifest-files-and-directives).
So the line ‘//= require_tree .’ is telling Sprokets to include all
files
which are in the same directory of the manifest file ( . ), included my
custom.js file.

// This is a manifest file that’ll be compiled into application.js,
which
will include all the files
// listed below.
//
// Any JavaScript/Coffee file within this directory,
lib/assets/javascripts, vendor/assets/javascripts,
// or any plugin’s vendor/assets/javascripts directory can be referenced
here using a relative path.
//
// It’s not advisable to add code directly here, but if you do, it’ll
appear at the bottom of the
// compiled file.
//
// Read Sprockets README
(GitHub - rails/sprockets: Rack-based asset packaging system) for details
// about supported directives.
//
//= require jquery
//= require jquery_ujs
//= require bootstrap
//= require turbolinks
//= require_tree .

4

Would rails automatically load this file or am I expected to explicitly tell
rails to load it?

What confuses me is that in the Ruby on Rails tutorial, when jQuery is used, it
is put inside the html.erb document, like in Chapter 13, so that on the one hand
it is used a custom.css.scss file as stylesheet, on the other hand, when
javascript is required, it is inserted inside the html.erb document.

If you use jQuery, you have to guarantee that it loads before you rely
on it. Load tree (the directive in the last line of application.js)
loads the app/assets/javascripts folder, as well as the
vendor/assets/javascripts folder, and any scripts declared by Gems, in
filesystem order. I don’t know the order of operations here off the top
of my head, but it seems likely that you would have a hard time
guaranteeing that jQuery was loaded before your script tried to use it,
particularly if your script name started with an i or lower letter.

Walter