How to group or merge this array of objects in javascript?

Question

I have an array of objects like below for example.

{name: \"Mc Donald\", quantity: 4, maleCount: 1, femaleCount: 0}
{name: \"KFC\", quantity: 9, maleCou         


        

Answer 1

My solution based on reduce:

let data = [
  {name: "Mc Donald", quantity: 4, maleCount: 1, femaleCount: 0},
  {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
  {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
  {name: "Mc Donald", quantity: 4, maleCount: 0, femaleCount: 1},
  {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1},
  {name: "KFC", quantity: 9, maleCount: 1, femaleCount: 0},
  {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1},
  {name: "KFC", quantity: 9, maleCount: 0, femaleCount: 1}
];

// We will only keep an array of values of the merged object
let result = Object.values(
  // Merge data to name indexed objects
  data.reduce((p,c) => {
    // Ensure key (name) exists
    if (!p[c.name]) {
       // If first occurence, duplicate object (to avoid modification of original array)
       p[c.name] = Object.assign({}, c);
    } else {
       // If key (name) already exists, sum up relevant attributes
       p[c.name].quantity += c.quantity;
       p[c.name].maleCount += c.maleCount;
       p[c.name].femaleCount += c.femaleCount;
    }
    // return updated object
    return p;
  }, {})
);

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

hope this will help