class Opal::BuilderProcessors::ERBProcessor

first get preprocessed via ERB, then served verbatim as JS.
This handler is for files named “.js.erb”, which ought to

def source 

def source
  erb = ::ERB.new(@source.to_s)
  erb.filename = @abs_path
  result = erb.result
  module_name = ::Opal::Compiler.module_name(@filename)
  "Opal.modules[#{module_name.inspect}] = function() {#{result}};"
end