修改地址后的参数：

<script>
function getNewUrl(oldurl,paramname,pvalue){
    var reg = new RegExp("(\\?|&)"+ paramname +"=([^&]*)(&|$)","gi");
    var t=oldurl.match(reg)[0];
    var retxt=t.substring(0,t.indexOf("=")+1)+pvalue;
    if(t.charAt(t.length-1)=='&') retxt+="&";
    return oldurl.replace(reg,retxt);
 }
 alert(getNewUrl("http://servername/virturlpath/index.asp?p1=123&p2=aa&p3=hh&p4=1","p4","cxz"));
</script>

　　获取地址参数：

<script>
function aa(source, name)
{
  var reg = new RegExp("(^|\\?|&)"+ name +"=([^&]*)(\\s|&|$)", "i"); 
  if (reg.test(source)) return RegExp.$2; return "";
};
alert(aa("http://community.csdn.net/Expert/topic/4223/4223277.xml?temp=6.502932E-02", "temp"))
</script>