javascript 2つの連想配列で一致箇所追加２

以下のような連想配列が2つあり、attendanceの方に名前nameのfirst と日付(date)が合えば、
dataの配列のvehicleとstaffのdepを追加する処理を記述しています。
しかし2点問題があります。

１）staffがnullの場合staff.depと記述すると以下のエラーが表示されてしまいます。
TypeError: Cannot read property 'dept' of null
なので以下のように記述しましたが、「injectData.indexOf is not a function」とエラーになってしまいます。

 if (injectData){
    if (injectData.indexOf(injectData.mdItemDto.name) == -1){
        target.mdItemDto = { mdItemDto: injectData.mdItemDto};
    }else{
        target.mdItemDto = { name: injectData.mdItemDto.name };
}

２）2つの配列で一致すれば追加という処理でnameのfirst が認識されません。

 function(dataN){ return ( target.date==dataN.date && target.name.first==dataN.name.fist ) }

上記2つの問題に関してご教示お願いいたします。

var attendance ={
    "obj1":{"date":"2015-01-01","name":{"first":"fist1","last":"last1"},"出勤":"09:00:00","退勤":"18:00:00"},
    "obj2":{"date":"2015-01-01","name":{"first":"fist2","last":"last2"},"出勤":"10:00:00","退勤":"20:00:00"},
    "obj3":{"date":"2015-01-02","name":{"first":"fist6","last":"last6"},"出勤":"09:00:00","退勤":"18:00:00"},
    "obj4":{"date":"2015-01-02","name":{"first":"fist7","last":"last7"},"出勤":"10:00:00","退勤":"20:00:00"}
};
var data ={
    "data1":{"date":"2015-01-01","name":{"first":"fist1","last":"last1"},"vehicle":"car", "staff":{"id":"01","dep":"sales"}},
    "data2":{"date":"2015-01-01","name":{"first":"fist2","last":"last2"},"vehicle":"car", "staff":{"id":"02","dep":"engineer"}},
    "data3":{"date":"2015-01-01","name":{"first":"fist3","last":"last3"},"vehicle":"train","staff":{"id":"03","dep":"bookkeeper"}},
    "data4":{"date":"2015-01-01","name":{"first":"fist4","last":"last4"},"vehicle":"train", "staff":{"id":"04","dep":"engineer"}},
    "data5":{"date":"2015-01-02","name":{"first":"fist5","last":"last5"},"vehicle":"train", "staff":{"id":"01","dep":"sales"}}
};


var attendance_and_vehicle = Object.keys(attendance).reduce( function(dict, key){
    var target = attendance[key];
    var injectData = Object.keys(data).map(
        function(key){ return data[key] 
        //document . write("data[key]: "data[key] +"<br>" );
        }
    ).filter(
        function(dataN){ return ( target.date==dataN.date && target.name.first==dataN.name.fist ) }
    )[0]
    if (injectData){
        target.vehicle = injectData.vehicle;
        target.staff = { dept: injectData.staff.dep };
    } else {
        target.vehicle = undefined;
        target.staff = { dept: undefined };        
    }
    dict[key]= target;
    return dict;
},{});