javascript验证url格式是否合法

function isURL(str_url) {// 验证url
    var strRegex = "^((https|http|ftp|rtsp|mms)?://)"
                       + "?(([0-9a-z_!~*'().&=+$%-]+: )?[0-9a-z_!~*'().&=+$%-]+@)?" // ftp    的user@
                       + "(([0-9]{1,3}\.){3}[0-9]{1,3}" // IP形式的URL- 199.194.52.184
                       + "|" // 允许IP和DOMAIN（域名）
                       + "([0-9a-z_!~*'()-]+\.)*" // 域名- www.
                       + "([0-9a-z][0-9a-z-]{0,61})?[0-9a-z]\." // 二级域名
                       + "[a-z]{2,6})" // first level domain- .com or .museum
                       + "(:[0-9]{1,4})?" // 端口- :80
                       + "((/?)|" // a slash isn't required if there is no file name
                       + "(/[0-9a-z_!~*'().;?:@&=+$,%#-]+)+/?)$";
    var re = new RegExp(strRegex);
    return re.test(str_url);
}