How to Use JavaScript in Ruby on Rails

How to use Javascript in Ruby on Rails?

Have you found this?

Where to Stick Your JavaScript.

Where to Stick Your JavaScript

Whether you use the Rails asset pipeline or add a <script> tag directly to a view, you have to make a choice about where to put any local JavaScript file.

We have a choice of three locations for a local JavaScript file:

• the app/assets/javascripts folder
• the lib/assets/javascripts folder
• the vendor/assets/javascripts folder

Here are guidelines for selecting a location for your scripts:

• Use app/assets/javascripts for JavaScript you create for your application.
• Use lib/assets/javascripts for scripts that are shared by many applications (but use a gem if you can).
• Use vendor/assets/javascripts for copies of jQuery plugins, etc., from other developers.

In the simplest case, when all your JavaScript files are in the app/assets/javascripts folder, there’s nothing more you need to do.

Add JavaScript files anywhere else and you will need to understand how to modify a manifest file.

Mysterious Manifests
There are two kinds of files in a JavaScript assets folder:

• ordinary JavaScript files
• manifest files
  
  You can also have CoffeeScript files and ERB files which are variations on ordinary JavaScript files.

Manifest files have the same .js file extension as ordinary JavaScript files. Manifest files and ordinary JavaScript files can be combined in a single file. This makes manifest files mysterious, or at least non-obvious.

The default app/assets/javascripts/application.js file is a manifest file. It’s a manifest file because it contains directives:

//= require jquery  
//= require jquery_ujs  
//= require_tree .

Directives tell Sprockets which files should be combined to build a single JavaScript script. Each file that contains manifest directives becomes a single JavaScript script with the same name as the original manifest file. Thus the app/assets/javascripts/application.js manifest file becomes the application.js script.

All scripts in the app/assets/javascripts folder are automatically added to the default application.js script when the manifest file includes the default //= require_tree . directive.

Hope this helps.

ruby on rails - add javascript

Adding your custom javascript to your rails app is real easy, just follow the steps below :-

• create a file (say custom.js) under app/assets/javascripts/
• Open up your manifest file i.e application.js (this is the file where you need to include every javascript file you want to load into your rails app, add the script name to it //=require custom.
• Visit your rails app from browser and check the page source and search for custom.js being loaded or not thats all.

Injecting ruby with javascript on Ruby on Rails

Have a look at the Working with JavaScript in Rails guide, specifically the section about how to respond from your Rails server with some JavaScript that then gets evaluated by the client ("rails-ujs").

This gives you all the powers you need (and can replace quite a lot what people nowadays use entire JS frameworks for, btw)

All you need is link_to ... remote: true to a path that is handled by a controller action that can respond_to ... format.js. Then you put a something.js.erb file into the correct place in your app/views folder and Rails does the rest for you.

Have a close look at the full guide to get the full picture and comment below if you still have questions. I'd be happy to extend my answer!

How to require custom JS files in Rails 6

Get better-organized code and avoid multiple javascript_pack_tags in your application.html.erb file with this approach:

1. Add your custom example.js javascript file to app/javascript/packs.
2. Add require("packs/example") to your application.js file.

---

I would have liked to add a comment to Asim Hashmi's correct answer. But I don't have enough reputation, so I'll add my suggestion as an answer instead.

It isn't necessary to include the ".js" extension inside of the require.

---

Related Topics