how to get parameters from url using js?

way 1：

<script. type="text/javascript">
<!--
String.prototype.getQuery = function(name) {
　　var reg = new RegExp("(^|&)"+ name +"=([^&]*)(&|$)");
　　var r = this.substr(this.indexOf("\?")+1).match(reg);
　　if (r!=null) return unescape(r[2]); return null;
}
var strHref = "www.xx.com/index.htm?a=aaa&b=bbb&c=ccc";
alert(strHref.getQuery("a"));
alert(strHref.getQuery("b"));
alert(strHref.getQuery("c"));
//-->
</script> 

way 2：

<script. type="text/javascript">
function getUrlPara(paraName){
var sUrl = location.href;
var sReg = "(?:\\?|&){1}"+paraName+"=([^&]*)"
var re=new RegExp(sReg,"gi");
re.exec(sUrl);
return RegExp.$1;
}
//应用实例：test_para.html?a=11&b=22&c=33
alert(getUrlPara("a"));
alert(getUrlPara("b"));
</script>

way 3：

<script. type="text/javascript">
<!--
function Request(strName){
var strHref = "www.xx.com/index.htm?a=aaa&b=bbb&c=ccc";
var intPos = strHref.indexOf("?");
var strRight = strHref.substr(intPos + 1);
var arrTmp = strRight.split("&");
for(var i = 0; i < arrTmp.length; i++) {
var arrTemp = arrTmp[i].split("=");
if(arrTemp[0].toUpperCase() == strName.toUpperCase()) return arrTemp[1];
}
return "";
}
alert(Request("a"));
alert(Request("b"));
alert(Request("c"));
//-->
</script>