remove old date by ObjectId

remove.js

var day  = 24*3600*1000;
var expiredTime = Date.now() - day *90;
var expiredDate = new Date(expiredTime);

var objectIdFromDate = function (date) {
	var idStr = Math.floor(date.getTime() / 1000).toString(16) + "0000000000000000";
	return new ObjectId(idStr);
};

db.tokens.remove({_id:{$lt:objectIdFromDate(expiredDate)}})