Convert array of object to object using Javascript

Question

I have following input

const testObj = [
    {id:1, name: 'name1',role:'Developer'},
    {id:2, name: 'name2',role:'Lead'},
    {id:3, name: 'name3',role:'QA'}
]

and i need to get the output in following format

{
    Developer: {id:1,name:'name1',role:'Developer'},
    Lead: {id:2,name:'name2',role:'Lead'},
    QA: {id:3,name:'name3',role:'QA'}
}

and i tried to write the following code but i am not getting my desired output

const convert = (array,role) => {
    var result = {}
    for(let index = 0; index < array.length; index++){
        result[array[index].id] = array[index].name;
    }
    return result;
}

and i am calling my method using following code

convert(testObj,'role');

How do i modify this method to get my desired output without using Reduce keyword and all

@JonasW.@bambam i mistakenly wrote my output with same role, now i updated my output. please check. — Nidhin Paul
– Nidhin Paul, Commented Jun 30, 2018 at 12:15
Possible duplicate of How to convert an array of objects to object with key value pairs — Kiran Joshi
– Kiran Joshi, Commented Jun 30, 2018 at 12:16

T.J. Crowder · Accepted Answer · 2018-06-30 12:14:14Z

You're not far off (if I assume the roles in the output should be like the roles in the input), but the body of your for should be

result[array[index].role] = array[index];

You were using the id rather than the role, and grabbing the name instead of the entire object.

Also note that there's no need for your second parameter (role) in the code you've shown or to go from your original to your new structure:

const testObj = [{id:1, name: 'name1',role:'Developer'},
{id:2, name: 'name2',role:'Lead'},
{id:3, name: 'name3',role:'QA'}]

const convert = (array) => {
  var result = {}
  for (let index = 0; index < array.length; index++) {
    result[array[index].role] = array[index];
  }
  return result
}

console.log(convert(testObj));

.as-console-wrapper {
  max-height: 100% !important;
}

We can simplify that a bit with for-of, though:

const testObj = [{id:1, name: 'name1',role:'Developer'},
{id:2, name: 'name2',role:'Lead'},
{id:3, name: 'name3',role:'QA'}];

const convert = (array) => {
  const result = {};
  for (const entry of array) {
    result[entry.role] = entry;
  }
  return result;
}

console.log(convert(testObj));

.as-console-wrapper {
  max-height: 100% !important;
}

Note that as Jonas W. points out, your result structure only allows for a single person in each role. You might want to have the object store arrays instead:

const testObj = [{id:1, name: 'name1',role:'Developer'},
{id:2, name: 'name2',role:'Lead'},
{id:3, name: 'name3',role:'QA'},
{id:4, name: 'name4',role:'QA'}]

const convert = (array) => {
  var result = {}
  for (let index = 0; index < array.length; index++) {
    var roleArray = result[array[index].role];
    if (!roleArray) {
      roleArray = result[array[index].role] = [];
    }
    roleArray.push(array[index]);
  }
  return result
}

console.log(convert(testObj));

.as-console-wrapper {
  max-height: 100% !important;
}

or, again, with for-of:

const testObj = [{id:1, name: 'name1',role:'Developer'},
{id:2, name: 'name2',role:'Lead'},
{id:3, name: 'name3',role:'QA'},
{id:4, name: 'name4',role:'QA'}];

const convert = (array) => {
  const result = {}
  for (const entry of array) {
    let roleArray = result[entry.role];
    if (!roleArray) {
      roleArray = result[entry.role] = [];
    }
    roleArray.push(entry);
  }
  return result;
}

console.log(convert(testObj));

.as-console-wrapper {
  max-height: 100% !important;
}

Jonas Wilms · Accepted Answer · 2018-06-30 12:15:08Z

1

Your code groups the .names by .id, you want to group the objects itself by their role:

function group(array, key) {
  const result = {};
  for(const obj of array)
    result[ obj[key] ] = obj;
  return result;
}

group(testObj, "role")

answered Jun 30, 2018 at 12:15

Jonas Wilms

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Comments

lnl · Accepted Answer · 2018-06-30 12:23:08Z

1

const testObj = [{id:1, name: 'name1',role:'Developer'},
{id:2, name: 'name2',role:'Lead'},
{id:3, name: 'name3',role:'QA'}];

const convert = (array, role) => {
	let i = 0;
  const output = {};
	for (; i < array.length; i+= 1) {
  	output[array[i][role]] = array[i];
  }
  return output;
}

console.log(convert(testObj, 'role'));

answered Jun 30, 2018 at 12:23

lnl

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Comments

saad maqsood · Accepted Answer · 2023-09-21 10:03:23Z

0

You can do this with .reduce

const testObj = [{id:1, name: 'name1',role:'Developer'},{id:2, name: 'name2',role:'Lead'},{id:3, name: 'name3',role:'QA'}],
        result = testObj.reduce((acc, cur) => {
            (acc[cur.role] = acc[cur.role] || []);
            acc[cur.role]=cur;
            return acc;
        }, {});
        
    console.log(result);

edited Sep 21, 2023 at 10:03

answered Sep 20, 2023 at 8:39

saad maqsood

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1 Comment

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