js比较两个数组对象,取出不同的值

var array1 = [ { "Num" :  "A "   },{ "Num" :  "B"  }];
var array2 = [ { "Num" :  "A " , "Name" :  "t1 "  }, { "Num" :  "B" , "Name" :  "t2" }, { "Num" :  "C "  , "Name" :  "t3 " }];
var result = [];
for (var i =  0 ; i < array2.length; i++){
    var obj = array2[i];
    var num = obj.Num;
    var isExist =  false ;
    for (var j =  0 ; j < array1.length; j++){
        var aj = array1[j];
        var n = aj.Num;
        if (n == num){
            isExist =  true ;
            break ;
        }
    }
    if (!isExist){
        result.push(obj);
    }
}
console.log(result);