js 字符串格式化

String.prototype.format = function(args) {
        var result = this;
        if (arguments.length > 0) {
            if (arguments.length == 1 && typeof (args) == "object") {
                for (var key in args) {
                    if(args[key]!=undefined){
                        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) {
                        var reg= new RegExp("({)" + i + "(})", "g");
                        result = result.replace(reg, arguments[i]);
                    }
                }
            }
        }
        return result;
    }