gistfile1.coffee

padding_left = (str, len) ->
  str = "#{str}"
  str  = "0#{str}" while str.length < len
  str

padding_right = (str, len) ->
  str = "#{str}"
  str = "#{str}0" while str.length < len
  str

console.log(padding_left 123, 5)    # 00123
console.log(padding_right 123, 5)   # 12300