使用Javascript自动将日期调整为每月的第二个星期六？

Question

我需要网站的 Javascript 代码来自动调整日期。目标是让代码自动将以下语句调整为从现在到永远每个月的第二个星期六：

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Next membership meeting: Saturday, MONTH, DAY, YEAR 11 a.m. to noon.

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有人有主意吗？非常感谢！

Answer 1

该函数将为您获取日期对象，您可以从中提取您需要的内容：

var getMeeting = function(year, month){
    var date = new Date(year, month, 1, 0, 0, 0, 0);
    date.setDate(14-date.getDay());
    return date;
};


alert(getMeeting(2011,5));

Answer 2

我没有测试，但这是基础知识：

//our main code
var Months = ["Jan", "Feb", "Mar", /*... you finish... */ ];
var meetingDate = getMonthlyMeeting();
document.Write( "<i>Next membership meeting:</i> Saturday, " + Months[meetingDate.getMonth()] + ", " + meetingDate.getDay() + ", " + meetingDate.getYear() + " 11 a.m. to noon.");



// call this to get the monthly meeting date
// returns a Date() object
function getMonthlyMeeting(){
var today = new Date(); //JS automatically initializes new Date()s to the current time

//first, see if today is our meeting day
var meetingDate;
var thisMonthsMeeting = getSecondTuesdayInMonth(today.getMonth(), today.getYear());
if( thisMonthsMeeting.getDay() == today.getDay() ){
  // today is our meeting day!
  meetingDate = today;
}
else {
 if  ( today.getDay() < thisMonthsMeeting.getDay() ){
   // it hasn't happened this month yet
   meetingDate = thisMonthsMeeting;
 } else {
   //this month's meeting day has already passed
   if( today.getMonth() == 11 ){
        // rolling over to the next year
        meetingDate = getSecondTuesdayInMonth(0, today.getYear() + 1);
   } else {
        meetingDate = getSecondTuesdayInMonth(today.getMonth() + 1, today.getYear());
   }
 }
}
return meetingDate;
}

// this is a helper function to get the second tuesday in any month
// returns a Date() object
function getSecondTuesdayInMonth(var month, var year){
var saturdays = 0;
var testDay= new Date();
while( testDay.getDay() != 2 && saturdays < 2 ){
  //while the day we are testing isnt tuesday (2) and we haven't found it twice
  if( testDay.getDay() == 2 )
    saturdays = saturdays + 1; //we found a saturday
  testDay= new Date(testDay.getTime() + 86400000); //increment our day to the next day
}
//when we finish the while loop, we are on our day
return testDay;
}

Answer 3

所以，我认为你的问题的核心是：我如何知道每个月的第二个星期六是什么？

未经测试，但这就是我想出的：
它是针对任何一个月的任何第 n 天进行抽象的。

    nthDate = function(nth_week, nth_day, month){
        var src_date = new Date();

        src_date.setDate(1);
        src_date.setMonth(month);

        return ( (nth_week * 7) - src_date.getDay() ) - ( Math.abs( nth_day - 6) );
    };

    var cur_date = new Date();

    var cur_day = cur_date.getDay();

    //2 for the 2nd week of the month
    //6 is the integer value for saturday (days of the week 0-6)
    var nth_date = nthDate( 2, 6, cur_date.getMonth() );

    if(cur_day < nth_date){
       //display the upcoming date here
    }else if( cur_day  > nth_date){
       //figure out next month's date and display that
       var next_date = nthDate(2, 6, (cur_date.getMonth() +1) );
       //does this deal with the case of the month being december?? not sure. 
    }

第 2 周在该月的 14 天范围内。

我们可以：

首先减去本月开始的星期几的偏移量，

然后第二：

我们可以减去我们要查找的星期几的偏移量。
（这需要是天数的偏移量，因此星期六是 0（零）偏移量。我们从第 n 天的绝对值减去一周中的天数得到这个值。

这给了我们 如果我们在第二个星期六

然后，因为您有一些整数，所以您可以对这些值进行简单的比较，

之前，则显示该日期，如果没有计算下个月的新日期，

希望有所帮助。