Question

I have a below JS where I get the max date that is user allowed to enter from a backend script:

var max_date = new Date(pdate + " " + ptime);

where pdate and ptime is fetched from a script.

Now I need to set the min date as 1 month less than max_date

if (max_date.getMonth() == 0)
subtractyear = 1;
var min_date = new Date(Date.UTC(max_date.getFullYear() - subtractyear,max_date.getMonth() - 1,max_date.getDate(),max_date.getHours(),0,0));

My issue is that if max_date is March 31 – then will the min_date be rolled over to Feb 28 or Feb 29 or Feb 31 or Feb 30?

If the date formed is an incorrect date – say Feb 30 how can I rectify this?

Answer 1

Simple subject the month by 1 would get a valid date — never would setMonth method return an invalid Date object (the same as setDate, setYear and the Date constructor):

var date = new Date(2012, 02, 31); // 2012-03-31
date.setMonth(date.getMonth() - 1); // This gets 2012-03-02

I don’t quite clear what date you expected, the last day of the previous month or just the day one month earlier?