subtract n days from data object code example
Example: javascript subtract days from date
var myCurrentDate=new Date();
var myPastDate=new Date(myCurrentDate);
myPastDate.setDate(myPastDate.getDate() - 8);//myPastDate is now 8 days in the past
var myCurrentDate=new Date();
var myPastDate=new Date(myCurrentDate);
myPastDate.setDate(myPastDate.getDate() - 8);//myPastDate is now 8 days in the past