pad '0' for Coffee script

pad.coffee

pad = (num, figs, char='0') =>
  prefix = new Array(figs + 1).join(char)
  (prefix + num).slice(-figs)

alert pad(12, 2)      # => 12
alert pad(5, 2)       # => 02
alert pad(12, 4)      # => 0012
alert pad(3, 4, '#')  # => ###3