How can i merge an array of objects with with a unique key?

Issue

i have the following array of objects.i want to merge these objects with month as a unique id.

[
  { month: 7, openSlot: 9, confirmed: 0, requested: 0, total: 0 },
  { month: 5, openSlot: 0, confirmed: 6, requested: 0, total: 0 },
  { month: 7, openSlot: 0, confirmed: 0, requested: 0, total: 17 }
]

The above array should be merged like this

  { month: 7, openSlot: 9, confirmed: 0, requested: 0, total: 17 },
 { month: 5, openSlot: 0, confirmed: 6, requested: 0, total: 0 }

Solution

You could do this using forEach and adding the values of each key. NB: if you are interested in a more optimized code, use the solution by @Nina Scholz

const data = [
  { month: 7, openSlot: 9, confirmed: 0, requested: 0, total: 0 },
  { month: 5, openSlot: 0, confirmed: 6, requested: 0, total: 0 },
  { month: 7, openSlot: 0, confirmed: 0, requested: 0, total: 17 }
]

function merge(data) {

  let tempObj = {};

  data.forEach(item => {

    if (tempObj[item['month']]) {
      let temp = {}
      Object.entries(item).forEach(([key, value]) => {

        temp[key] = key === 'month' ? value : value + tempObj[item['month']][key];

      })
      tempObj[item['month']] = temp

    } else {
      tempObj[item['month']] = item
    }

  });

  return tempObj;
}

console.log(Object.values(merge(data)));

Answered By - kiranvj