Question

72

Retrieving Keys from JSON Array key-value pair dynamically - Javascript

rated 0 times [ 78] [ 6] / answers: 1 / hits: 49606 / 13 Years ago, mon, september 12, 2011, 12:00:00

I have a question that would like to seek your expertise on.

This is a JSON array that I have:

[{A:20,B:32,C:27,D:30,E:40}]

What I would like to do is to retrieve the keys (A, B, C, D, E) from the JSON array instead of the values. I am able to retrieve the values but not the keys.

I am using this to retrieve the values dynamically:

function calculateSum(jsonArray) {

    var result = 0;

    for (var i = jsonArray.length - 1;  i >= 0; --i)

    {

        var o = jsonArray[i];

        A = o.A;

        B = o.B;

        C = o.C;

        D = o.D;

        E = o.E;

        result = A + B + C + D + E;

        return result;

    }



    return result;

}

Similarly, what should I do to retrieve the keys using JavaScript?

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lucianod

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answered 13 Years ago levidaylonj · Accepted Answer

Are you using D3.js as your tag implies? Because in that case, you can just use d3.keys():

var data = [{A:20,B:32,C:27,D:30,E:40}];

d3.keys(data[0]); // [A, B, C, D, E]

If you want the sum of all the values, you might be better off using d3.values() and d3.sum():

var data = [{A:20,B:32,C:27,D:30,E:40}, {F:50}];

// get total of all object totals

var total = d3.sum(data, function(d) {

    // get total of a single object's values

    return d3.sum(d3.values(d));

});

total; // 199