esbuild for Rails

Use esbuild to bundle your JavaScript, then deliver it via the asset pipeline in Rails. This gem provides an installer to get you going with esbuild in a new Rails application, and a convention to use app/assets/builds to hold your bundled output as artifacts that are not checked into source control (the installer adds this directory to .gitignore by default).

You develop using this approach by running esbuild in watch mode in a terminal with yarn build --watch (and your Rails server in another, if you’re not using something like puma-dev). Whenever esbuild detects changes to any of the JavaScript files in your project, it’ll bundle app/javascript/application.js into app/assets/builds/javascript.js (and all other entry points placed in the root of app/javascript). You can refer to the build output in your layout using the standard asset pipeline approach with <%= javascript_include_tag "application" %>.

When you deploy your application to production, esbuild attaches to the assets:precompile task to ensure that all your package dependencies from package.json have been installed via npm, and then runs yarn build to process all the entry points, as it would in development. The latter files are then picked up by the asset pipeline, digested, and copied into public/assets, as any other asset pipeline file.

This also happens in testing where esbuild attaches to the test:prepare task to ensure the JavaScript has been compiled before testing commences. (Note that this currently only applies to rails test:* tasks (like test:all or test:controllers), not “rails test”, as that doesn’t load test:prepare).

That’s it!

You can tailor the configuration of esbuild through the build script in package.json. Or if you want to get fancy with plugins, you can setup an external configuration to run through node.

Installation

You must already have node and yarn installed on your system. Then:

  1. Add esbuild-rails to your Gemfile with gem 'esbuild-rails'
  2. Run ./bin/bundle install
  3. Run ./bin/rails esbuild:install

Or, in Rails 7+, you can preconfigure your new application to use esbuild with rails new myapp -j esbuild.

The sister gem to rollupjs-rails

This gem is almost identical in setup and purpose to rollupjs-rails, which follows the same conventions, but uses rollup.js instead.

License

esbuild for Rails is released under the MIT License.