Using variable keys to access values in JavaScript objects

Question

The code:

function updateDashboardData() {
    $.getJSON("includes/system/ajaxDataInterface.php", {recordcount:1}, function(data) {
        $('.stationContainer').each(function(data) {
            var bsID = $(this).attr("id");
            var bsStatus = $(this).children('.stationStatus');
            alert(data[bsID][0].time);
            bsStatus.find('.bs_maxHandsets').text(data[bsID][0].maxHandsets);
            bsStatus.find('.bs_time').text(data[bsID][0].time);
        });
    });
}

The object data:

{
    "A5A50000": [{
        "bsid": "A5A50000",
        "chanCount": 17,
        "time": "2009-05-27 16:36:45",
        "avgInterference": 1.711765,
        "maxInterference": 4.97,
        "avgHandsets": 205.1176,
        "maxHandsets": 315,
        "avgCalls": 6.4118,
        "maxCalls": 13,
        "avgCBA": 3868.98059,
        "maxCBA": 7463,
        "sumSuccessCBA": 197318,
        "sumTimeoutHandoff": 133,
        "sumAttemptHandoff": 1028,
        "sumDeniedHandoff": 216,
        "sumConfirmHandoff": 679,
        "sumHandoffNetwork": 61873,
        "sumJoinNetwork": 96888,
        "sumLeaveNetwork": 93754,
        "sumRcvdKeepalive": 98773,
        "sumTimeoutKeepalive": 19748,
        "sumAttemptUplink": 93689,
        "sumBlockedUplink": 62453
    }]
}

The problem:

alert(data.A5A50000[0].time); properly displays "2009-05-27 16:36:45".

alert(bsID); properly displays "A5A50000".

alert(data.bsID[0].time); reports "data.bsID is undefined".

alert(data[bsID][0].time); reports "data[bsID] is undefined".

I'm a little unclear when a variable is/isn't evaluated. Maybe I'm overlooking something silly, but I can't figure out my problem here.

Answer 1

In Javascript, you can use either object or array-style notation to look up an attribute. The following are equivalent:

data.A5A50000
data['A5A50000']

With the second syntax, you can use a variable in place of an object string:

data[bsID][0]

Answer 2

I experienced the same problem with a nested JSON API-response:

[
    {
        "bj_code": "2019",
        "BJ_PERIODE": [
            {
                "nummer": 1
            },
            {
                "nummer": 2
            }
        ]
    }
]   

I could evaluate:

pm.expect(pm.response.json()[0].BJ_PERIODE[1].nummer).to.eql(2);

But working with BJ_PERIODE and nummer through a variable didn't work. Writing it with the bracket method did work, even in this nested JSON, like this:

const periode = "BJ_PERIODE";
const nr = "nummer"; 
pm.expect(pm.response.json()[0][periode][1][nr]).to.eql(2);