将月份映射到该月的最后一天

Question

考虑到2月leap年的最后一天是28，我如何将月份数字映射到该月最后一天的数字，否则是29

Answer 1

Sure, you can get the last day of the month like this:

 var month = 1; // Feb var date = new Date((new Date()).getYear(), month + 1, 0); alert("Last day of the month is: " + date.getDate()); 

Here it is as a function:

function getLastDayOfMonth(month) {
   return (new Date((new Date()).getYear(), month + 1, 0)).getDate();
}