Group values into arrays by key in array of objects

Question

I want to get the following output

expected output

[
  { name: 'mega-service', amount: [ 15, 22 ] },
  { name: 'somethingElse', amount: [ 12, 112 ] },
  { name: 'sms-alert', amount: [ 22 ] },
]

code i have written

const data = [
  {clientServiceName: "mega-service", amount: 15},
  {clientServiceName: "somethingElse", amount: 12},
  {clientServiceName: "somethingElse", amount: 112},
  {clientServiceName: "mega-service", amount: 22},
  {clientServiceName: "sms-alert", amount: 22}
]

const result = [];

data.forEach(d => {
  if(result.length === 0){
    let obj = {
      name: d.clientServiceName,
      amount: [d.amount]
    }
    result.push(obj);
  }else{
    result.forEach(r => {
      if(r.name === d.clientServiceName){
        r.amount = [...r.amount, d.amount]
        // console.log("inside name match")
      }else{
        let anotherObj = {
          name: d.clientServiceName,
          amount: [d.amount]
        }
        result.push(anotherObj);
      }
    })
  }
})

console.log(result)

But i am getting following output

output

[
  { name: 'mega-service', amount: [ 15, 22 ] },
  { name: 'somethingElse', amount: [ 12, 112 ] },
  { name: 'somethingElse', amount: [ 112 ] },
  { name: 'mega-service', amount: [ 22 ] },
  { name: 'mega-service', amount: [ 22 ] },
  { name: 'sms-alert', amount: [ 22 ] },
  { name: 'sms-alert', amount: [ 22 ] },
  { name: 'sms-alert', amount: [ 22 ] },
  { name: 'sms-alert', amount: [ 22 ] },
  { name: 'sms-alert', amount: [ 22 ] }
]

where did i get wrong here to get expected output. please help me to get my expected output

prasanth · Answer 1 · 2021-08-15T15:02:56.370

3

You can do with Array#reduce

const data = [ {clientServiceName: "mega-service", amount: 15}, {clientServiceName: "somethingElse", amount: 12}, {clientServiceName: "somethingElse", amount: 112}, {clientServiceName: "mega-service", amount: 22}, {clientServiceName: "sms-alert", amount: 22} ]


const res =  Object.values(data.reduce((acc,{clientServiceName:name,amount})=>(
   acc[name] = acc[name] || {name,amount:[]},
   acc[name]['amount'].push(amount)
   , acc
),{}))

console.log(res)

edited Aug 15 '21 at 15:02

answered Aug 15 '21 at 14:51

prasanth

22,145
4
29
53

I was in the process of writing something similar but this is *way* cleaner than I was going to do. I was going to check if the item existed and then either insert or append, but this is better. – Dillan Wilding Aug 15 '21 at 14:59

score 1 · Answer 2 · edited Sep 09 '21 at 12:45

Use an object instead of array to group the common names, then use Object.values() to return array from that object

const data = [
  { clientServiceName: 'mega-service', amount: 15 },
  { clientServiceName: 'somethingElse', amount: 12 },
  { clientServiceName: 'somethingElse', amount: 112 },
  { clientServiceName: 'mega-service', amount: 22 },
  { clientServiceName: 'sms-alert', amount: 22 },
];

const group = {};

data.forEach(({ clientServiceName: name, amount }) => {  
  group[name] = group[name] || { name, amount: [] };
  group[name].amount.push(amount);
});

const res = Object.values(group);
console.log(res);

score 0 · Answer 3 · answered Aug 15 '21 at 14:59

This does the job the way you wanted it.

let result = [];
data.forEach(item => {
    let index = result.findIndex(resultItem => resultItem.name === item.clientServiceName);
  if (index > -1) {
    result[index].amount.push(item.amount);
  } else {
    result.push({ name: item.clientServiceName, amount: [ item.amount ] });
  }
});

score 0 · Answer 4 · answered Aug 15 '21 at 15:03

You can achieve the result by combination of reduce and find method

const data = [
  {clientServiceName: "mega-service", amount: 15},
  {clientServiceName: "somethingElse", amount: 12},
  {clientServiceName: "somethingElse", amount: 112},
  {clientServiceName: "mega-service", amount: 22},
  {clientServiceName: "sms-alert", amount: 22}
]


const answer = data.reduce((accum, cur) => {
  let obj = accum.find(x => x.name === cur.clientServiceName);

  
  if (obj) {
    obj.amount.push(cur.amount);
    return accum;
  } else {
    return [...accum, {name: cur.clientServiceName, amount: [cur.amount]}]
  }
}, [])

console.log(answer)

score -5 · Answer 5 · answered Aug 15 '21 at 14:50

-5

You can use the array.filter() function.

Look a the documentation :

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/filter

answered Aug 15 '21 at 14:50

Dupeyrat Kevin

66
4

This is not an helpfull answer in any way – LeeLenalee Aug 15 '21 at 14:52
Yep your right reduce() make the job, I didn't understand the question ✌️ – Dupeyrat Kevin Aug 15 '21 at 18:55

Group values into arrays by key in array of objects

5 Answers5