改变原型

Date.prototype.Format = function (fmt) { //
    var o = {
        "M+": this.getMonth() + 1, //Month
        "d+": this.getDate(), //Day
        "h+": this.getHours(), //Hour
        "m+": this.getMinutes(), //Minute
        "s+": this.getSeconds(), //Second
        "q+": Math.floor((this.getMonth() + 3) / 3), //Season
        "S": this.getMilliseconds() //millesecond
    };
    if (/(y+)/.test(fmt)) fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
    for (var k in o)
        if (new RegExp("(" + k + ")").test(fmt)) fmt = fmt.replace(RegExp.$1, (RegExp.$1.length == 1) ? (o[k]) : (("00" + o[k]).substr(("" + o[k]).length)));
    return fmt;
};