Javascript date subtract going back (Pentaho)

Question

How to subtract date with day..

eg;- curdate: 20130207 Orginal date has to be : 20130206,2010205, 20130204,..., 20130201, 20130131, 20130130,etc..

How to do this with javascript (or the calculator step if you know Pentaho)?

Say, I want go all the days going back for 90 days.

Puzzled.

Answer 1

Use setDate and getDate:

var yesterday = new Date();
yesterday.setDate(yesterday.getDate() - 1));

Or, for all your 90 days:

d = new Date();
for (i = 1; i <= 90; i++) {
   d.setDate(d.getDate() - 1);
   console.log(i+" days ago: "+d);
}

Answer 2

Use something like:

var d1 = new Date(2012, 1, 6) // date(year, month - 1, day)
days= -90; //# of days
var d2 = new Date(d1.setDate(d1.getDate() + days));

DEMO: http://jsfiddle.net/dirtyd77/qZWJE/