set/access multiple keys

gistfile1.coffee

update_in = (obj, keys, value) ->
  node = obj
  while true
    key = keys.shift()
    if keys.length > 0
      node[key] = {} unless node[key]?
      node = node[key]
    else
      node[key] = value
      break
  obj

# Look up multiple nested keys
# For example, get_in({a:{b:99}}, ["a", "b"]) => 99
get_in = (obj, keys, deflt = null) ->
  x = null
  node = obj
  while true
    key = keys.shift()
    if keys.length > 0
      node = node[key]
      return deflt unless node?
    else
      x = node[key]
      break
  if x? then x else deflt