Javascript group .json key value into list

Question

I have the following json file structure that includes years from 2008 to 2020, along with other keys such as location, name, etc.:

{"2008": 50, "2009": 60, "2010": 70, "2011": 80, etc...}

I am trying to group the years into another key and adding it to the original array:

{metric:
    [{"year": 2008, "perc": 50},
     {"year": 2009, "perc": 60},
     {"year": 2010, "perc": 70},
     {"year": 2011, "perc": 80}],
 "2008": 50, 
 "2009": 60,
 "2010": 70,
 "2011": 80,
 etc...
}

I think I need to create a range between 2008 to 2020, and if I detect a key that's within that range, I add to the metrics group and add that to the array?

JSON is a *textual notation* for data exchange. [(More here.)](http://stackoverflow.com/a/2904181/157247) If you're dealing with JavaScript source code, and not dealing with a *string*, you're not dealing with JSON. — T.J. Crowder, Feb 28 '21 at 08:44

score 2 · Accepted Answer · answered Feb 28 '21 at 08:49

What you have is an object, not an array. You can use a for-in loop or a for-of loop on Object.entries or similar to loop through the object, and then it's a matter of converting the year to a number and comparing it to your range and if it's in range, adding it to the metric array:

const data = {"2008": 50, "2009": 60, "2010": 70, "2011": 80, "2001": 20, "2002:": 30};
// Loop through the object
for (const [year, perc] of Object.entries(data)) {
    // Get the year as a number
    const yearValue = +year; // See note below
    if (yearValue >= 2008 && yearValue <= 2020) {
        // It's in range, get or create the `metric` array
        const metric = data.metric ?? (data.metric = []);
        // Add to it
        metric.push({year, perc});
    }
}

console.log(data);

(I added a couple of out-of-range years there to show the range working.)

Using unary + to convert to number is just one of your options, I go through the full range of them in my answer here.

score 0 · Answer 2 · answered Feb 28 '21 at 09:00

you need to loop though the object and create a new one

const group => obj {
    // create init object
    let output = {
        metric: []
    }

    // start loop
    for (const key in obj) {

        // check if object contains property
        if (Object.hasOwnProperty.call(obj, key)) {

            // check if key matches range and assign to metric if not
            if (!(/20(0[8-9]|1[0-9]|20)/gm).test(key)) output.metric.push({
                'year': key,
                'perc': obj[key]
            });
                
            //assign value if matches between 2008 to 2020
            else output[key] = obj[key]
        }
    }

    // return new object
    return output;
}

Javascript group .json key value into list

2 Answers2