js prototype属性，类似.net扩展方法

prototype 属性使您有能力向对象添加属性和方法。

类似.net扩展方法

定义：

String.prototype.toWeekName = function () {
    var newDate = new Date(this.replace(/-/g, '/'));
    var weekday = new Array();
    weekday[] = "星期日";
    weekday[] = "星期一";
    weekday[] = "星期二";
    weekday[] = "星期三";
    weekday[] = "星期四";
    weekday[] = "星期五";
    weekday[] = "星期六";
    return weekday[newDate.getDay()];
}

调用

            var day = new Date();
            var month = (day.getMonth() + ) <  ? ("" + (day.getMonth() + )) : (day.getMonth() + );
            var date = day.getDate() <  ? ("" + day.getDate()) : day.getDate();
            var dayformat = day.getFullYear() + "-" + month + "-" + date;
            var week = dayformat.toWeekName();//调用