Convert a string with dots('.') to a tree structure

create_tree.js

var lst = function(array){return array.slice(-1);}
var head = function(array){return array.slice(0,-1);}

  
function CreateTree(key){
  keys = key.split('.')
  tags = {}
  var last = lst(keys)
  var hd = head(keys)
  while(hd.length!==0){
    tags[hd.join(".")] = last[0]
    last = lst(hd)
    hd = head(hd)
  }
  return tags
}