Como converter String para Array no MongoDB?

db.collection.find().forEach( function (x) {   
    lines = x.address.split(",");
    obj = {};
    userAddressList = [];
    lines.forEach( function (address){
        addressArray = address.replace(/^\s\s*/, '').replace(/\s\s*$/, '').split(" ");
        obj[addressArray[0]] = !isNaN(parseInt(addressArray[1])) ? parseInt(addressArray[1]) : addressArray[1];        
    });
    obj.building = "";
    obj.intercom = "";
    userAddressList.push(obj);
    x.userAddressList = userAddressList; // convert field to string
    db.collection.save(x);
});