Javascript date range of last three quarters and current quarter till yesterday

This is pretty small code, but took me a while to figure it out. So mentioning here just in case I would need to use it in the future.

// Show last 3 quarters (plus this quarter)
endDate = new Date();
var noOfQuarters = 3;
var quarter = Math.floor((endDate.getMonth() + 3) / 3);
startDate = new Date(endDate.getFullYear(), endDate.getMonth() - (noOfQuarters * 3 + endDate.getMonth() - (quarter - 1) * 3));