Javascript - sum up quantity in occured products inside an array of objects

Question

I have the following array like this

[
 {name: "calpol", quantity: 12},
 {name: "paracetamol", quantity: 15},
 {name: "paracetamol", quantity: 10},
]

and I want to sum up the quantity when the product is the same so i can get an array like :

[
 {name: "calpol", quantity: 12},
 {name: "paracetamol", quantity: 25},
]

https://stackoverflow.com/questions/29364262/how-to-group-by-and-sum-array-of-object — epascarello, Mar 25 '19 at 18:15

score 2 · Answer 1 · answered Mar 25 '19 at 18:17

Use reduce and in the accumulator array check if there exist a object with a name such as calpol or paracetamol. If it exist then update the quantity else create new object and push it in the accumulator

let prod = [{
    name: "calpol",
    quantity: 12
  },
  {
    name: "paracetamol",
    quantity: 15
  },
  {
    name: "paracetamol",
    quantity: 10
  },
]

let sum = prod.reduce(function(acc, curr) {
  let findIndex = acc.findIndex(item => item.name === curr.name);

  if (findIndex === -1) {
    acc.push(curr)
  } else {

    acc[findIndex].quantity += curr.quantity
  }
  return acc;
}, [])

console.log(sum)

Javascript - sum up quantity in occured products inside an array of objects

1 Answers1