Adding a parameter to URL string using Coffeescript.

add_parameter_to_url.coffee

@addAttributeToUrl: (url, key, val) ->
  return url if _.some arguments, (arg) ->
    arg == null or arg == ''

  #regex = (all non-# or non-?)(0-1: # or ?)(all non-blanks)
  regex = /([^\?#]*)([?#]?)([^\s]*)/
  match = regex.exec(url.trim())
  baseUrl = match[1]
  separator = match[2]
  queryString = match[3]

  url = "#{baseUrl}?#{key}=#{val}"
  if queryString
    separator = "&" if separator is "?"
    url += separator + queryString
  url