A quick ruby script to extract sources from a JS sourcemap

sourcemap_to_tar.rb

require 'json'
require 'rubygems/package'

unless ARGV.length == 1
  puts "Usage: ruby sourcemap_to_tar.rb <sourcemap_file>"
  exit 1
end

sourcemap_filename = ARGV.shift
sourcemap = JSON.parse(File.read(sourcemap_filename))

source_filenames = sourcemap['sources'].map { |x| x.sub(%r{^webpack:///}, '').sub(%r{^\./}, '') }
source_contents = sourcemap['sourcesContent']

File.open("#{sourcemap_filename}.tar", "wb") do |file|
  Gem::Package::TarWriter.new(file) do |tar|
    source_filenames.zip(source_contents).each do |filename, content|
      tar.add_file(filename, 0644) do |io|
        io.write(content)
      end
    end
  end
end