字符串格式化---- String.prototype.format

String.prototype.format = function (args) {
            return this.replace(/\{(\w+)\}/g, function (g0, g1) {    # g0,g1表示函数前的参数字符串的索引
                return args[i];
            });
        };

例2：

//扩展 string.format
String.prototype.format = function () {
    var args = arguments;
    var reg = /\{(\d+)\}/g;
    return this.replace(reg, function (g0, g1) {    
        return args[+g1];       
    });
};
//用法:
var k="a{0}b{1}".format("qqq","www");