bootstrap navbar auto activation in coffeescript

tb-nav-auto-activation.coffee

# get relative path of URL
getPath = (url) ->
  path = url.split(window.location.host)[1] or '/'
  path + if path.match '/$' then '' else '/'  # ensure endsWith '/'

# check whether p is parent of path (starts with)
parentOf = (p, path) ->
  unless p is '/' then path.match '^' + p
  else p == path  # '/' should not matches any path

$(document).ready ->
  path = getPath document.URL  # get current path

  # activates current path, excluding dropdown-menu
  $('.nav li a').not('.dropdown-menu a').each ->
    navPath = getPath this.href
    if parentOf navPath, path
      $(this).closest('li').addClass 'active'