convert camelcase to snakecase in coffeescript

camelToSnake

obj = {'someThing':'else',"BlahBlah":"bLah","sealTeam":6}
defaults = {'some_thing':'more',"seal_team":2}

camelToSnake = (s)->
  s = s.replace /^([A-Z]+)/, (match) ->
    if match.length == 1
      match.toLowerCase()
    else
      "#{match.slice(0,match.length-1).toLowerCase()}_#{match.slice(match.length-1).toLowerCase()}"
  s = s.replace /([A-Z]+)$/, (match) ->
    "_#{match.toLowerCase()}"
  s = s.replace /([A-Z]+)/g, (match) ->
    if match.length == 1
      "_#{match.toLowerCase()}"
    else
      "_#{match.slice(0,match.length-1).toLowerCase()}_#{match.slice(match.length-1).toLowerCase()}"

for key of obj
    defaults[camelToSnake(key)] = obj[key]

console.log defaults