Recursive Object -> Query String in CoffeeScript

gistfile1.coffee

#
# Recursively converts an object into a query string
#
to_query_string = (data)->

  map = (hash, prefix='')->
    result = []

    for key, value of hash
      key = if prefix is '' then key else "#{prefix}[#{key}]"

      if typeof(value) is 'object'
        if value instanceof Array
          for v in value
            result.push(["#{key}[]", v])
        else if value # assuming it's an object
          for entry in map(value, key)
            result.push(entry)

      else
        result.push([key, "#{value}"])

    result

  data = for e in map(data)
    "#{encodeURIComponent(e[0])}=#{encodeURIComponent(e[1])}"

  data.join('&')