javascript时间函数

//js格式化时间
//"yyyy-MM-dd hh:mm:ss"
Date.prototype.format = function (format) {
    var date = {
        "M+": this.getMonth() + 1,
        "d+": this.getDate(),
        "h+": this.getHours(),
        "m+": this.getMinutes(),
        "s+": this.getSeconds(),
        "q+": Math.floor((this.getMonth() + 3) / 3),
        "S+": this.getMilliseconds()
    };
    if (/(y+)/i.test(format)) {
        format = format.replace(RegExp.$1, (this.getFullYear() + '').substr(4 - RegExp.$1.length));
    }
    for (var k in date) {
        if (new RegExp("(" + k + ")").test(format)) {
            format = format.replace(RegExp.$1, RegExp.$1.length == 1
                            ? date[k] : ("00" + date[k]).substr(("" + date[k]).length));
        }
    }
    return format;
}
//时间加天数
Date.prototype.addDays = function (day, format) {
    this.setDate(this.getDate() + day);
    return this.format(format);
}
//时间加周数
Date.prototype.addWeeks = function (w) {
    this.addDays(w * 7);
};
//时间加月数
Date.prototype.addMonths = function (m) {
    var d = this.getDate();
    this.setMonth(this.getMonth() + m);

    if (this.getDate() < d)
        this.setDate(0);
};
//时间加年数
Date.prototype.addYears = function (y) {
    var m = this.getMonth();
    this.setFullYear(this.getFullYear() + y);

    if (m < this.getMonth()) {
        this.setDate(0);
    }
};
//根据日期，起得第几周
Date.prototype.getWeek = function () {
    return new Array("星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六")[this.getDay()];
}
//获取参数，如:字符串（'?a=hello&b=world'），window.location.search.parameter('a');
String.prototype.parameter = function (name) {
    var reg = new RegExp("(^|&)" + name + "=([^&]*)(&|$)");
    var r = this.substr(1).match(reg);
    if (r != null) return unescape(r[2]); return null;
}