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

More functional/universal approach

const normalizeValue = (value) => value === undefined ? 0 : value
const sumUpProps = (props = []) => (a = {}, b = {}) => {
  const result = {}
  
  props.forEach((prop) => {
    result[prop] = normalizeValue(a[prop]) + normalizeValue(b[prop])
  })

  return result
}

const 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}
]

const entries = {}
const sumObjects = sumUpProps(['quantity', 'maleCount', 'femaleCount'])

data.forEach((item) => {
  const entry = entries[item.name] || {}

  entries[item.name] = sumObjects(entry, item)
})


console.log(entries)