if (typeof String.prototype.startsWith != 'function') {
    // see below for better implementation!
    String.prototype.startsWith = function (str) {
        return this.indexOf(str) == 0;
    };
}

$(document).ready(function () {
    $("#headermenu a").each(function () {
        var $a = $(this);
        var href = $a.attr("href");

        var path = $.trim(location.pathname.toLowerCase());
        var menuHref = $.trim(href.toLowerCase());

        if (href && (path == menuHref || (menuHref != '/' && path.startsWith(menuHref)))) {
            //صفحه جاری را یافتیم
            $a.css({
                "color": "Yellow",
                "border-bottom": "2px solid"
            });
        }
    });
});

public static bool IsItNumber(this string inputvalue)
{
  var isnumber = new Regex("[^0-9]");
  return !isnumber.IsMatch(inputvalue);
}