JAVASCRIPT:时间格式化

date.prototype.format.js

/**
* 对Date的扩展，将 Date 转化为指定格式的String
* 月(M)、日(d)、12小时(h)、24小时(H)、分(m)、秒(s)、周(E)、季度(q) 可以用 1-2 个占位符
* 年(y)可以用 1-4 个占位符，毫秒(S)只能用 1 个占位符(是 1-3 位的数字)
* eg:
* (new Date()).pattern("yyyy-MM-dd hh:mm:ss.S") ==> 2007-07-02 08:09:04.423
* (new Date()).pattern("yyyy-MM-dd E HH:mm:ss") ==> 2007-03-10 二 20:09:04
* (new Date()).pattern("yyyy-MM-dd EE hh:mm:ss") ==> 2007-03-10 周二 08:09:04
* (new Date()).pattern("yyyy-MM-dd EEE hh:mm:ss") ==> 2007-03-10 星期二 08:09:04
* (new Date()).pattern("yyyy-M-d h:m:s.S") ==> 2007-7-2 8:9:4.18
*/
Date.prototype.format = function(fmt) {
    var o = {
        "M+": this.getMonth() + 1,
        //月份
        "d+": this.getDate(),
        //日
        "h+": this.getHours() % 12 == 0 ? 12 : this.getHours() % 12,
        //小时
        "H+": this.getHours(),
        //小时
        "m+": this.getMinutes(),
        //分
        "s+": this.getSeconds(),
        //秒
        "q+": Math.floor((this.getMonth() + 3) / 3),
        //季度
        "S": this.getMilliseconds() //毫秒
    };
    var week = {
        "0": "\u65e5",
        "1": "\u4e00",
        "2": "\u4e8c",
        "3": "\u4e09",
        "4": "\u56db",
        "5": "\u4e94",
        "6": "\u516d"
    };
    if (/(y+)/.test(fmt)) {
        fmt = fmt.replace(RegExp.$1, (this.getFullYear() + "").substr(4 - RegExp.$1.length));
    }
    if (/(E+)/.test(fmt)) {
        fmt = fmt.replace(RegExp.$1, ((RegExp.$1.length > 1) ? (RegExp.$1.length > 2 ? "\u661f\u671f": "\u5468") : "") + week[this.getDay() + ""]);
    }
    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;
}
//test
//alert((new Date()).format("yyyy-MM-dd EEE hh:mm:ss"));

Date.prototype.format = function (mask) { 
    var d = this;

    var zeroize = function (value, length) {

            if (!length) length = 2;

            value = String(value);

            for (var i = 0, zeros = ''; i < (length - value.length); i++) {

                zeros += '0';

            }

            return zeros + value;

        };

    return mask.replace(/"[^"]*"|'[^']*'|/b ( ? : d {
        1, 4
    } | m {
        1, 4
    } | yy( ? : yy) ? | ([hHMstT]) / 1 ? | [lLZ]) / b / g, function ($0) {

        switch ($0) {

        case 'd':
            return d.getDate();

        case 'dd':
            return zeroize(d.getDate());

        case 'ddd':
            return ['Sun', 'Mon', 'Tue', 'Wed', 'Thr', 'Fri', 'Sat'][d.getDay()];

        case 'dddd':
            return ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday'][d.getDay()];

        case 'M':
            return d.getMonth() + 1;

        case 'MM':
            return zeroize(d.getMonth() + 1);

        case 'MMM':
            return ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep', 'Oct', 'Nov', 'Dec'][d.getMonth()];

        case 'MMMM':
            return ['January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December'][d.getMonth()];

        case 'yy':
            return String(d.getFullYear()).substr(2);

        case 'yyyy':
            return d.getFullYear();

        case 'h':
            return d.getHours() % 12 || 12;

        case 'hh':
            return zeroize(d.getHours() % 12 || 12);

        case 'H':
            return d.getHours();

        case 'HH':
            return zeroize(d.getHours());

        case 'm':
            return d.getMinutes();

        case 'mm':
            return zeroize(d.getMinutes());

        case 's':
            return d.getSeconds();

        case 'ss':
            return zeroize(d.getSeconds());

        case 'l':
            return zeroize(d.getMilliseconds(), 3);

        case 'L':
            var m = d.getMilliseconds();

            if (m > 99) m = Math.round(m / 10);

            return zeroize(m);

        case 'tt':
            return d.getHours() < 12 ? 'am' : 'pm';

        case 'TT':
            return d.getHours() < 12 ? 'AM' : 'PM';

        case 'Z':
            return d.toUTCString().match(/[A-Z]+$/);

            // Return quoted strings with the surrounding quotes removed      

        default:
            return $0.substr(1, $0.length - 2);

        }

    });

};

https://www.cnblogs.com/zhangpengshou/archive/2012/07/19/2599053.html