group the object in array by name [duplicate]

Question

let obj = [
    {
        name: "a",
        quantity: 2
    },
    {
        name: "b",
        quantity: 4
    },
    {
        name: "c",
        quantity: 88
    }
]

let obj2 = [
    {
        name: "a",
        quantity: 2
    }
]

I want to group two object array but if object which has a same name already exists then merge.

For example, there are objects which name is "a" and I want to merge them together.

Output what I want is like

[
    {
        name: "a",
        quantity: 4
    },
    {
        name: "b",
        quantity: 4
    },
    {
        name: "c",
        quantity: 88
    }
]

The quantity of object which name is "a" is add together. Is there anyway to do this?

Answer 1

You can use forEach() for this.

let obj = [
    {
        name: "a",
        quantity: 2
    },
    {
        name: "b",
        quantity: 4
    },
    {
        name: "c",
        quantity: 88
    }
]

let obj2 = [
    {
        name: "a",
        quantity: 2
    }
]

obj.forEach((element)=>{
obj2.forEach((e)=>{
  if(element.name == e.name){
  element.quantity = element.quantity+e.quantity
    }
  })
})

console.log(obj);

Answer 2

let obj = [
    {
        name: "a",
        quantity: 2
    },
    {
        name: "b",
        quantity: 4
    },
    {
        name: "c",
        quantity: 88
    }
]

let obj2 = [
    {
        name: "a",
        quantity: 2
    }
]

let obj3 = [...obj, ...obj2];

let obj4 = obj3.reduce( (curr, ele) => {
  let exist = curr.filter( cur => cur.name == ele.name)
  if (exist.length) exist[0].quantity += ele.quantity
  else curr.push(ele)
  return curr
}, [])

console.log(obj4)