Merge specific properties of objects together with JavaScript

Question

So I have an array of objects like so:

[
  {
    name: "Joe Smith",
    job: "Custodian",
    age: 35,
    id: "3421"
  },
  {
    n         


        

Answer 1

By using reduce to iterate through the array to build a new one, and simply check if the id is already inserted then concatenate the job otherwise insert the new object:

const arr = [
  { name: "Joe Smith", job: "Janitor", age: 35, id: "3421" },
  { name: "George Henderson", job: "CEO", age: 43, id: "5098" },
  { name: "Joe Smith", job: "Cook", age: 35, id: "3421" },
  { name: "Sam Doe", job: "Technician", age: 22, id: "1538" },
  { name: "Joe Smith", job: "Dishwasher", age: 35, id: "3421" } 
]

const result = arr.reduce((acc, cur) => {
    const duplicate = acc.find(e => e.id == cur.id)
    
    if (duplicate) {
	duplicate.job += ', ' + cur.job
    } else {
	acc.push(cur)
    }

    return acc
}, [])

console.log(result)