Traversing object by given path

traverse = (obj, path, callback) ->
  i = 0

  do (obj) ->
    key = path[i]
    i++

    if typeof obj[key] is 'object'
      arguments.callee obj[key]
    else
      callback obj, key

obj =
  foo: 
    bar: 'Old value'

path = ['foo', 'bar']

callback = (obj, key) ->
  obj[key] = 'New value'


traverse obj, path, callback