Javascript grouping

How can I add data by grouping with country label and create data array that has 12 index indicating months and containing value of data before grouping. I need help, how to push and group the data according to the month number. e.x

arr = [
  { label: 'US', data: '10', monthNumber: 1 },
  { label: 'US', data: '2', monthNumber: 3  },
  { label: 'US', data: '60', monthNumber: 2  },
  { label: 'UK', data: '10', monthNumber: 5 },
  { label: 'SA', data: '1', monthNumber: 1  },
  { label: 'CA', data: '70', monthNumber: 1  },
  { label: 'SA', data: '10', monthNumber: 12 },
];

now i need the results to be like

[
  { label: 'US', data: [10,60,2,0,0,0,0,0,0,0,0,0] },
  { label: 'UK', data: [0,0,0,0,10,0,0,0,0,0,0,0] },
  { label: 'SA', data: [1,0,0,0,0,0,0,0,0,0,0,10] },
  { label: 'CA', data: [70,0,0,0,0,0,0,0,0,0,0,0] },
];

Solution

Create a new object by reducing over the array using the labels as object keys, and initialising the property value as an object with a label, and a pre-filled array of zeros. Then update the array with the data at the relevant position.

const arr=[{label:"US",data:"10",monthNumber:1},{label:"US",data:"2",monthNumber:3},{label:"US",data:"60",monthNumber:2},{label:"UK",data:"10",monthNumber:5},{label:"SA",data:"1",monthNumber:1},{label:"CA",data:"70",monthNumber:1},{label:"SA",data:"10",monthNumber:12}];

function grouper(arr) {

  // `reduce` over the array passing in an
  // empty object as the initial accumulator value
  const out = arr.reduce((acc, c) => {

    // Destructure the properties from the current
    // iterated object
    const { label, data, monthNumber } = c;

    // If the label doesn't exist as a key on the object
    // create it, and assign an object as its value, using
    // the label, and adding a pre-filled array of zeros to
    // its data property
    acc[label] ??= { label, data: new Array(12).fill(0) };

    // Update the data array with the data value at the
    // appropriate position
    acc[label].data[monthNumber - 1] = Number(data);

    // Return the accumulator for the next iteration
    return acc;

  }, {});

  // Finally get the array of updated objects
  // from the accumulated data
  return Object.values(out);
  
}

console.log(grouper(arr));

Additional documentation