How to convert array of objects (key-value pair) to nested arrays only

Question

This is what I currently have.

[
    [
        {"label":"Year","type":"number"},
        {"label":"Value","type":"number"},
    ],
    {"2013" : 70}, 
    {"2014" : 78}, 
    {"2015" : 125}, 
    {"2016" : 153}
]

this is what I am using to generate the above code.

var data = [
    {"Year":2013,"Product":"A","Value":0},
    {"Year":2013,"Product":"B","Value":20},
    {"Year":2013,"Product":"A","Value":50},
    {"Year":2014,"Product":"D","Value":55},
    {"Year":2014,"Product":"M","Value":23},
    {"Year":2015,"Product":"D","Value":73},
    {"Year":2015,"Product":"A","Value":52},
    {"Year":2016,"Product":"B","Value":65},
    {"Year":2016,"Product":"A","Value":88}
];

var sum = data.reduce(function(res, product) {

  if (!(product.Year in res)) {
    res[product.Year] = product.Value;
  } else {
    res[product.Year] += product.Value;
  }
  return res;
}, {});

var result = [];

for (var year in sum) {
  var tmp = {};
  tmp[year] = sum[year];
  result.push(tmp);
}
result.splice(0, 0, [{
  label: 'Year',
  type: 'number'
}, {
  label: 'Value',
  type: 'number'
}]);

and I want to organize them into [Year, Value] pairs instead of objects, like this:

[["Year", "Value"], ["2013", 70], ["2014", 78], ["2015", 125], ["2016", 153]]

Answer 1

You are pushing objects ({}) into the array. What you want is to use the array brackets instead ([]) in the second line shown below:

for (var year in sum) {
  var tmp = [];
  tmp[year] = sum[year];
  result.push(tmp);
}