js中的string.format函数代码

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;
    }
}

String.prototype.format = function(args)
{

if (!String.prototype.format) {

    String.prototype.format = function() {

        var str = this.toString();

        if (!arguments.length)

            return str;

        var args = typeof arguments[0],

            args = (("string" == args || "number" == args) ? arguments : arguments[0]);

        for (arg in args)

            str = str.replace(RegExp("\\{" + arg + "\\}", "gi"), args[arg]);

        return str;

    }

}

}

　　//两种调用方式 
var template1="我是{0}，今年{1}了"; 
var template2="我是{name}，今年{age}了"; 
var result1=template1.format("loogn",22); 
var result2=template1.format({name:"loogn",age:22}); 
//两个结果都是"我是loogn，今年22了"