getCommonDirectory of two paths

index.coffee

Path = require "path"

getDirectories = (path) ->
  dirs = []
  path = Path.resolve path unless Path.isAbsolute path
  dirs.push Path.basename path if Path.extname(path) is ""
  loop
    dir = Path.dirname path
    break if dir is "/"
    dirs.push dir.slice dir.lastIndexOf("/") + 1
    path = dir
  return dirs

getCommonDirectory = (a, b) ->
  result = []
  b = Path.resolve b unless Path.isAbsolute b
  dirs = { a: getDirectories(a), b: getDirectories(b) }
  loop
    dir = { a: dirs.a.pop(), b: dirs.b.pop() }
    break unless dir.a? and dir.b?
    result.push dir.a if dir.a is dir.b
  return if result.length > 0 then result.join "/" else null