Rails 6 introduces parameterized mailers in ActionMailer
Rails 6 adds parameterized mailers, allowing mailer defaults like `@user` or `@order` to be reused across methods.
GAURAV VARMA
Rails 6 makes Webpacker the default JavaScript pipeline
Rails 6 officially replaces the asset pipeline for JavaScript with Webpacker, enabling modern JavaScript tooling and ES6 support.
Rails 6 adopts Zeitwerk autoloader by default
Rails 6 adopts Zeitwerk as the default code loader, bringing thread-safety, consistency, and improved autoloading behavior.
Rails 6 brings parallel testing to speed up CI
Rails 6 introduces built-in parallel test execution, reducing CI times significantly by running tests across multiple processes.
Rails 6 supports multiple databases in one app
Rails 6 introduces built-in support for multiple databases, allowing developers to scale with read replicas, isolate domains with separate databases, and manage migrations independently.