js方法获取get方式传过来的参数

有两种方法：比如url为：http://h5.49you.com/reg.html?sid=1&a=2&b=3&c=4

1、function GetQueryString(name) {

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

var sid = GetQueryString("sid");

var a = GetQueryString("a");

       var b = GetQueryString("b");

var c = GetQueryString("c");

2、var $_GET = (function() {
 var url = window.document.location.href.toString();
 var u = url.split("?");
 if (typeof(u[1]) == "string") {
   u = u[1].split("&");
   var get = {};
   for (var i in u) {
     var j = u[i].split("=");
     get[j[0]] = j[1];
   }
   return get;
 } else {
   return {};
 }
})();

var sid=ad = $_GET['sid'];

       var a=ad = $_GET['a'];

       var b=ad = $_GET['b'];

       var c=ad = $_GET['c'];