JS regular get URL parameter code

Use JS get url parameter method and PHP tutorial, ASP tutorial is not the same, if said in PHP to get a.php?id=www.111cn.net direct $_get[' a '] on Ko, but to use processing is not the same, the following look at an example.

function Geturlparam (name) {
var reg = new RegExp ("(^|&)" + name + "= ([^&]*) (&|$)");
var r = window.location.search.substr (1). Match (REG);
if (R!= null)
Return unescape (r[2]);
return null;
}

He wants to use location to process, this function calls the method Geturlparam (' id ') is OK.