Where can i find the database file?

[Dingdash]

var ForerunnerDB = require("forerunnerdb"),
fdb = new ForerunnerDB(),
DB = fdb.db("fortas");
DB.debug(true);
DB.persist.auto(true);
DB.persist.dataDir("../DB");
module.exports = DB;
I did this. if i see my DB folder it's empty but the database works fine.