javascript 我怎样才能用js获得一个月的4个星期一？
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How can I get the 4 Mondays of a month with js?
提问by Gaelle
I'm building a chart where the x-axis should be the four weeks of a month. I would like to display only the four Mondays of that month.
我正在构建一个图表，其中 x 轴应该是一个月的四个星期。我只想显示那个月的四个星期一。
I already have the currentMonthand the currentYearvariables, and I know how to get the first day of the month. All I need is to get the four Mondays of a month in an array. And all of this in the same JavaScript file.
我已经有了currentMonth和currentYear变量，并且我知道如何获得该月的第一天。我所需要的只是在数组中获取一个月的四个星期一。所有这些都在同一个 JavaScript 文件中。
I'm pretty lost within my programming logic, and I've seen plenty of solutions that don't fit my use case.
我完全迷失在我的编程逻辑中，而且我看到了很多不适合我的用例的解决方案。
Right now, I have:
现在，我有：
var date = new Date();
var currentYear = date.getFullYear();
var currentMonth = date.getMonth();
var firstDayofMonth = new Date(currentYear, currentMonth, 1);
var firstWeekDay = firstDayofMonth.getDay();
but I would like to have something like this:
但我想要这样的东西：
var myDates = [
new Date(firstMonday),
new Date(secondMonday),
new Date(thirdMonday),
new Date(fourthMonday),
];
回答by jabclab
The following functionwill return all Mondays for the current month:
以下function将返回当月的所有星期一：
function getMondays() {
var d = new Date(),
month = d.getMonth(),
mondays = [];
d.setDate(1);
// Get the first Monday in the month
while (d.getDay() !== 1) {
d.setDate(d.getDate() + 1);
}
// Get all the other Mondays in the month
while (d.getMonth() === month) {
mondays.push(new Date(d.getTime()));
d.setDate(d.getDate() + 7);
}
return mondays;
}
回答by KooiInc
This would return the fourthlast monday of month [m] in year [y]
这将返回[y] 年 [m] 月的第四个星期一
function lastmonday(y,m) {
var dat = new Date(y+'/'+m+'/1')
,currentmonth = m
,firstmonday = false;
while (currentmonth === m){
firstmonday = dat.getDay() === 1 || firstmonday;
dat.setDate(dat.getDate()+(firstmonday ? 7 : 1));
currentmonth = dat.getMonth()+1;
}
dat.setDate(dat.getDate()-7);
return dat;
}
// usage
lastmonday(2012,3); //=>Mon Mar 26 2012 00:00:00 GMT+0200
lastmonday(2012,2) //=>Mon Feb 27 2012 00:00:00 GMT+0100
lastmonday(1997,1) //=>Mon Jan 27 1997 00:00:00 GMT+0100
lastmonday(2012,4) //=>Mon Apr 30 2012 00:00:00 GMT+0200
To be more generic, this will deliver the last any weekday of a month:
为了更通用，这将提供一个月的最后一个工作日：
function lastDayOfMonth(y,m,dy) {
var days = {sun:0,mon:1,tue:2,wed:3,thu:4,fri:5,sat:6}
,dat = new Date(y+'/'+m+'/1')
,currentmonth = m
,firstday = false;
while (currentmonth === m){
firstday = dat.getDay() === days[dy] || firstday;
dat.setDate(dat.getDate()+(firstday ? 7 : 1));
currentmonth = dat.getMonth()+1 ;
}
dat.setDate(dat.getDate()-7);
return dat;
}
// usage
lastDayOfMonth(2012,2,'tue'); //=>Tue Feb 28 2012 00:00:00 GMT+0100
lastDayOfMonth(1943,5,'fri'); //=>Fri May 28 1943 00:00:00 GMT+0200
