Get the parameters of the address bar

function getUrlParam (name) {
  var reg = new RegExp('(^|&)' + name + '=([^&]*)(&|$)') // Construct a regular expression object with target parameters
  var r = window.location.search.substr(1).match(reg) // match target parameter
  if (r != null) return unescape(r[2]); return null // return parameter value
}