How can javascript extract specified key value from json blob with many nested values?

Question

I have an https query which returns a json blob in the following format:

{
"metric_data": {
    "from": "2021-12-09T01:25:32+00:00",
    "to": "2021-12-09T01:55:32+00:00",
    "metrics_not_found": [],
    "metrics_found": [
        "Mobile/Crash/All"
    ],
    "metrics": [
        {
            "name": "Mobile/Crash/All",
            "timeslices": [
                {
                    "from": "2021-12-09T01:24:00+00:00",
                    "to": "2021-12-09T01:54:00+00:00",
                    "values": {
                        "call_count": 5
                    }
                }
            ]
        }
    ]
}

}

I want to find and extract the value for call_count. What is the best way to do that with Javascript? The following code will actually print out all the json values, including the call_count but all my efforts to just grab the value for call_count are failing.

var json = `{
"metric_data": {
    "from": "2021-12-09T01:25:32+00:00",
    "to": "2021-12-09T01:55:32+00:00",
    "metrics_not_found": [],
    "metrics_found": [
        "Mobile/Crash/All"
    ],
    "metrics": [
        {
            "name": "Mobile/Crash/All",
            "timeslices": [
                {
                    "from": "2021-12-09T01:24:00+00:00",
                    "to": "2021-12-09T01:54:00+00:00",
                    "values": {
                        "call_count": 5
                    }
                }
            ]
        }
    ]
}
}`;
    
    // Convert a JSON object to a Javascript object
var obj = JSON.parse(json);

// This function prints nested values
function printValues(obj) {
    for(var k in obj) {
        if(obj[k] instanceof Object) {
            printValues(obj[k]);
        } else {
            document.write(obj[k] + "<br>");
        };
    }
};

// Printing all the values from the resulting object
printValues(obj);

document.write("<hr>");
    
    // This is where I fail as I try to print a single value.
    document.write(obj["metrics"]["call_count"] + "<br>");

Any feedback would be much appreciated!

Answer 1

Yes, well first there is the metric_data attribute you have ignored. Then metrics is an array of objects. Your snippet has one object in it, but it's still an array of objects. An object in that array has timeslices, which is an array of objects.

var json = `{
"metric_data": {
    "from": "2021-12-09T01:25:32+00:00",
    "to": "2021-12-09T01:55:32+00:00",
    "metrics_not_found": [],
    "metrics_found": [
        "Mobile/Crash/All"
    ],
    "metrics": [
        {
            "name": "Mobile/Crash/All",
            "timeslices": [
                {
                    "from": "2021-12-09T01:24:00+00:00",
                    "to": "2021-12-09T01:54:00+00:00",
                    "values": {
                        "call_count": 5
                    }
                }
            ]
        }
    ]
}
}`;
    
    // Convert a JSON object to a Javascript object
var obj = JSON.parse(json);

console.log(obj.metric_data.metrics[0].timeslices[0].values.call_count);