javascript format 的使用

1.javascript  format 的使用

<script>
String.prototype.format = function(args)
    {
        if (arguments.length > 0)
        {
            var result = this;
            if (arguments.length == 1 && typeof (args) == "object")
            {
                for (var key in args)
                {
                    var reg = new RegExp("({" + key + "})", "g");
                    result = result.replace(reg, args[key]);
                }
            }
            else
            {
                for (var i = 0; i < arguments.length; i++)
                {
                    if (arguments[i] == undefined)
                    {
                        return "";
                    }
                    else
                    {
                        var reg = new RegExp("({[" + i + "]})", "g");
                        result = result.replace(reg, arguments[i]);
                    }
                }
            }
            return result;
        }
        else
        {
            return this;
        }
    }
    var id="11";
   var url="/download?file={0}&token={1}&dbtype={2}".format(id,"2111144","JYDD"));
</script>