Datorama JSON - Group by number (variable) of dimensions (objects) and convert to a dictionary (array of objects) in Javascript

Datorama JSON - Group by number (variable) of dimensions (objects) and convert to a dictionary (array of objects) in Javascript

//Group JSON string by a number of dimensions (number is a variable) and convert to a dictionary (array of objects) in Javascript
<div style="background:yellow; "id="original"></div>
<div style="background:red;" id="output"></div>

<script>
var json_data = {"headers":["Month","Value","Number"],"rows":[["2018-10-01 00:00:00.0","one",209],["2018-10-01 00:00:00.0","one",274],["2018-09-01 00:00:00.0","five",183],["2018-10-01 00:00:00.0","five",164],["2018-09-01 00:00:00.0","four",214],["2018-09-01 00:00:00.0","four",192]]};
//const json_data = {Query.JSON};
  
//Group by function 
function groupBy(rows, numObjects) {
  const 
    rowMap = new Map(),
    result = [],
    dataTemp = [];
    
  // Iterate over the rows.
  rows.forEach(row => {
    // Create a key, it is the first elements joined together.
    const key = row.slice(0,numObjects).join();
    // Check if the Map has the generated key...
    if (rowMap.has(key)) {
      // The map has the key, we need to add up the values
      // Get the value for the current key.
      const storedRow = rowMap.get(key);
        // Add the value of the current row to the row in the map.
        storedRow[2] += row[2];
    } else {
      // The key doens't exist yet, add the row to the map.
      rowMap.set(key, row);
    }
  });
  // Iterate over all the entries in the map and push each value with the summed up value into the array.
  rowMap.forEach(value => {
    result.push(value);
  });
    
	for (i = 0; i < result.length; i++) 
	{
    var object = {"date": result[i][0].slice(0,10), "Value": result[i][1], "num": result[i][2]};
    dataTemp.push(object);      
	}

	return dataTemp;
}

data = groupBy(json_data.rows,2);

document.getElementById("output").innerHTML =JSON.stringify(data);
</script>