Combiner

The Combiner filter merges reopened modules and classes into a single definition.

Ruby allows reopening modules and classes to add methods across multiple files or locations:

module Foo
  def bar; end
end

module Foo
  def baz; end
end

JavaScript doesn’t support this pattern. The Combiner filter merges all definitions with the same name into a single definition:

const Foo = {
  bar() {},
  baz() {}
}

Usage

This filter is not included in the default filter set. It’s primarily useful when:

• Using the Require filter to inline multiple files that define the same module/class
• Self-hosting scenarios where Ruby source is split across files but needs to compile to a single JavaScript output

When using with the Require filter, Combiner should be applied after Require so that inlined files get their classes/modules merged with the main file.

Ruby2JS.convert(source, filters: [:require, :combiner])

Features

• Merges multiple definitions of the same module or class
• Handles nested module/class definitions
• Reorders class bodies to put class variable assignments (@@var) before methods (required for JavaScript’s evaluation order)