Iconmap for Rails

Like Importmap Rails, but for Icons.

Iconmap for Rails is automatically included in Rails 7+ for new applications, but you can also install it manually in existing applications:

1. Run ./bin/bundle add iconmap-rails
2. Run ./bin/rails iconmap:install

At their core, iconmaps are essentially a string substitution for what are referred to as "bare module specifiers". A "bare module specifier" looks like this: import React from "react". This is not compatible with the ES Module loader spec. Instead, to be ESM compatible, you must provide 1 of the 3 following types of specifiers:

• Absolute path:

import React from "/Users/DHH/projects/basecamp/node_modules/react"

• Relative path:

import React from "./node_modules/react"

• HTTP path:

import React from "https://ga.jspm.io/npm:react@17.0.1/index.js"

Iconmap-rails provides a clean API for mapping "bare module specifiers" like "react" to 1 of the 3 viable ways of loading ES Module javascript packages.

For example:

# config/iconmap.rb
pin "react", to: "https://ga.jspm.io/npm:react@17.0.2/index.js"

means "everytime you see import React from "react" change it to import React from "https://ga.jspm.io/npm:react@17.0.2/index.js""

import React from "react"
// => import React from "https://ga.jspm.io/npm:react@17.0.2/index.js"

The icon map is setup through Rails.application.iconmap via the configuration in config/iconmap.rb. This file is automatically reloaded in development upon changes, but note that you must restart the server if you remove pins and need them gone from the rendered iconmap or list of preloads.

It makes sense to use logical names that match the package names used by npm, such that if you later want to start transpiling or bundling your code, you won't have to change any module imports.

If you want to import local js module files from app/javascript/src or other sub-folders of app/javascript (such as channels), you must pin these to be able to import them. You can use pin_all_from to pick all files in a specific folder, so you don't have to pin each module individually.

# config/iconmap.rb
pin_all_from 'app/javascript/src', under: 'src', to: 'src'

The :to parameter is only required if you want to change the destination logical import name. If you drop the :to option, you must place the :under option directly after the first parameter.

Allows you to:

// app/javascript/application.js
import { ExampleFunction } from 'src/example_function'

Which imports the function from app/javascript/src/example_function.js.

Note: Sprockets used to serve assets (albeit without filename digests) it couldn't find from the app/javascripts folder with logical relative paths, meaning pinning local files wasn't needed. Propshaft doesn't have this fallback, so when you use Propshaft you have to pin your local modules.

Iconmap for Rails downloads and vendors your icons via JavaScript CDNs that provide pre-compiled distribution versions.

You can use the ./bin/iconmap command that's added as part of the install to pin, unpin, or update icons in your icon map. This command uses an API from JSPM.org to resolve your package dependencies efficiently, and then add the pins to your config/iconmap.rb file. It can resolve these dependencies from JSPM itself, but also from other CDNs, like unpkg.com and jsdelivr.com.

./bin/iconmap pin @fortawesome/fontawesome-free/svgs/brands/github.svg --from=jsdelivr
Pinning "@fortawesome/fontawesome-free/svgs/brands/github.svg" to vendor/icons/@fortawesome/fontawesome-free/svgs/brands/github.svg via download from https://cdn.jsdelivr.net/npm/@fortawesome/fontawesome-free@6.7.2/svgs/brands/github.svg

This will produce pins in your config/iconmap.rb like so:

pin "@fortawesome/fontawesome-free/svgs/brands/github.svg", to: "@fortawesome--fontawesome-free--svgs--brands--github.svg" # @6.7.2

The packages are downloaded to vendor/icons, which you can check into your source control, and they'll be available through your application's own asset pipeline serving.

If you later wish to remove a downloaded pin:

./bin/iconmap unpin @fortawesome/fontawesome-free/svgs/brands/github.svg
Unpinning and removing "@fortawesome/fontawesome-free/svgs/brands/github.svg"

By default, Rails loads icon map definition from the application's config/iconmap.rb to the Iconmap::Map object available at Rails.application.iconmap.

You can combine multiple icon maps by adding paths to additional icon map configs to Rails.application.config.iconmap.paths. For example, appending icon maps defined in Rails engines:

# my_engine/lib/my_engine/engine.rb

module MyEngine
  class Engine < ::Rails::Engine
    # ...
    initializer "my-engine.iconmap", before: "iconmap" do |app|
      app.config.iconmap.paths << Engine.root.join("config/iconmap.rb")
      # ...
    end
  end
end

And pinning JavaScript modules from the engine:

# my_engine/config/iconmap.rb

pin_all_from File.expand_path("../app/assets/javascripts", __dir__)

You can selectively import your javascript modules on specific pages.

Create your javascript in app/javascript:

// /app/javascript/checkout.js
// some checkout specific js

Pin your js file:

# config/iconmap.rb
# ... other pins...
pin "checkout", preload: false

Import your module on the specific page. Note: you'll likely want to use a content_for block on the specifc page/partial, then yield it in your layout.

<% content_for :head do %>
  <%= javascript_import_module_tag "checkout" %>
<% end %>

Important: The javascript_import_module_tag should come after your javascript_iconmap_tags

<%= javascript_iconmap_tags %>
<%= yield(:head) %>

Iconmap for Rails provides two commands to check your pinned packages:

• ./bin/iconmap outdated checks the NPM registry for new versions
• ./bin/iconmap audit checks the NPM registry for known security issues

Iconmap for Rails is released under the MIT License.