How do I calculate the date in JavaScript three months prior to today?

I Am trying to form a date which is 3 months before the current date. I get the current month by the below code

var currentDate = new Date();
var currentMonth = currentDate.getMonth()+1;

Can you guys provide me the logic to calculate and form a date (an object of the Date data type) considering that when the month is January (1), 3 months before date would be OCtober (10)?