Get last monday in month in moment.js

问题:

Is there a way that I get the last monday in the month with moment.js?

I know I can get the end of the month with: moment().endOf('month')

But how about the last monday?

回答1:

you get always monday with isoweek:

moment().endOf('month').startOf('isoweek')

回答2:

You're almost there. You just need to add a simple loop to step backward day-by-day until you find a Monday:

result = moment().endOf('month');
while (result.day() !== 1) {
    result.subtract(1, 'day');
}
return result;

回答3:

moment().endOf('month').day('Monday')

回答4:

I made a dropin for this, once you install/add it, so you can do:

moment().endOf('month').subtract(1,'w').nextDay(1)

That code gets the end of the month, minus 1 week, and then the next Monday.

To simplify this, you could do:

days = moment().allDays(1) //=> mondays in the month
days[days.length - 1] //=> last monday

Which gets all the Mondays in the month, and then selects the first one.

You could simplify it further like this:

moment().allDays(1).pop()

But this removes the Monday from the list - but if you aren't using the list (as in the example above), it shouldn't matter. If it does, you might want this:

moment().allDays(1).last()

But it requires a pollyfill:

if (!Array.prototype.last){
    Array.prototype.last = function(){
        return this[this.length - 1];
    };
};