获取url中的某个字段的值

 function getUrl(name, url) {
  url = url || window.location.search;
  var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)", "i");
  var r = url.substr(1).match(reg);
  if (r != null) return (r[2]);
  return null;
},
getUrl('id')