Javascript获取url中的参数

function GetUrlParms(parmsName) {
            var parms = window.location.href.split('?')[1];
            if (parms == null || parms == "")
                return;
            var arr = parms.split('&');

            if (arr.length > 1) {
                for (var i = 0; i < arr.length; i++) {
                    var name = arr[i].substring(0, arr[i].indexOf("="));
                    if (name == parmsName) {
                        var begin = arr[i].indexOf("=");
                        var end = arr[i].length;
                        alert(arr[i].substring(begin + 1, end));
                        return arr[i].substring(begin + 1, end);
                    }
                }
            } else {
                var begin = parms.indexOf("=");
                var end = parms.length;
                alert(parms.substring(begin + 1, end));
                return parms.substring(begin + 1, end);
            }
        }