let d = new Date(); d.setMonth(d.getMonth() - 3);var d = new Date(); d.setMonth(d.getMonth() - 3);const oneMonthAgo = new Date(Date.now() - 30 * 24 * 60 * 60 * 1000);var someDate = new Date(); // add arguments as needed someDate.setTime(someDate.getTime() - 3*28*24*60*60); // assumes the definition of "one month" to be "four weeks".