unchain_vars.rb

# Converts global chained `var`s into single-line vars.
#
# Example:
#
# >> cat test.js
# var A = require('a'),
#     B = require('b'),
#     C = B.C;
#
# var D = function() {};
#
# >> ruby unchain_vars.rb test.js
#
# >> cat test.js
# var A = require('a');
# var B = require('b');
# var C = B.C;
#
# var D = function() {};
#
filename = ARGV[0]
active = false
result = ''

File.open(filename).each do |line|
  if line =~ /^var .*,$/
    active = true
  end

  if active
    result << line.gsub(/^(var | +)(.+)[,;]$/, 'var \2;')
  else
    result << line
  end

  if active && line =~ /;$/
    active = false
  end
end
File.write(filename, result)

I made it able to take multiple filenames: https://gist.github.com/lencioni/b638689132e6c3a665c4