How to add a property to an object in VkScript (not through ".")?

Question

In contact with

There is this code:

var source = Args.source;
var targets = Args.targets;
// var common_friends = {};
var common_friends = [];
var req;
var parametr = "";
var start = 0;

// из строки с целями вынимаем каждую цель
while(start<=targets.length-1){
    if (targets.substr(start, 1) != "," && start != targets.length-1){
        parametr = parametr + targets.substr(start, 1);
    }
    else {
        // сразу делаем запросы, как только вытащили id
        req = API.friends.getMutual({"source_uid":source, "target_uid":parametr});
        common_friends = common_friends + req;
        // а нужно common_friends[parametr] = req; VkScript похоже не поддерживает
        parametr = "";
    }
    start = start + 1;
}

return common_friends;

The stored procedure in VKontakte takes as parameters: source (id) and targets(25 id separated by commas). Next, we extract targets by id and use them to get an array of mutual friends.
Now all this information needs to be sent back in a readable form:

{'id': [список общих друзей], 'id': [], 'id': [friend_id1, friend_id2],

But as I understand it, it is impossible to add a property to an object using square brackets - the usual

var a = {};
a["name"] = 123;

Returns error: non-variable in assignment
How else can you add a property to an object in VkScript?

var a = {};
a.name = 123;

In my case, not very suitable.

Answer 1

var a = {"cname":456};
var b = {"name":123};
a = a + b;
return a;

Return

response: {
cname: 456,
name: 123
}