What is the most efficient way to convert an array of objects to an object

Question

Trying to convert an array of objects to a single object and the array I have is similar to the following;

const array = [{id: '1', name: 'First'}, {id: '2', name: 'Second'}];

Expected output:

{'first': 1, 'second': 2}

Additionally, I want to change the casing of all values to lower case. Can assume that there are no spaces in between for the values for names. And all the ids are numbers.

Performance-wise, is there a better approach than this?

const array = [{id: '1', name: 'First'}, {id: '2', name: 'Second'}];
console.log(array);
const result = array.reduce((accumulator, value) => {return {...accumulator, [value.name.toLowerCase()]: Number(value.id)}}, {});
console.log(result);

Nick · Accepted Answer · 2020-11-19 21:13:58Z

2

A simple for ... of (or similar) will likely be most performant as it has no overhead of function calls. For example:

const array = [
  {id: '1', name: 'First'},
  {id: '2', name: 'Second'}
];

let result = {};

for (o of array) {
  result[o.name.toLowerCase()] = parseInt(o.id);
}
console.log(result);

edited Nov 19, 2020 at 21:13

answered Nov 19, 2020 at 21:08

Nick

147k23 gold badges67 silver badges106 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Khab · Accepted Answer · 2020-11-19 20:59:03Z

1

I think using a standard loop (for or while) would be the most efficient performance wise since it doesn't come with any additional stuff like map,reduce,sort do.

answered Nov 19, 2020 at 20:59

Khab

1046 bronze badges

Comments

Nina Scholz · Accepted Answer · 2020-11-19 20:58:58Z

0

You could create entries and generate an object from it.

const
    array = [{ id: '1', name: 'First' }, { id: '2', name: 'Second' }],
    object = Object.fromEntries(array.map(({ id, name }) => [name.toLowerCase(), +id]));

console.log(object);

answered Nov 19, 2020 at 20:58

Nina Scholz

388k26 gold badges367 silver badges417 bronze badges

2 Comments

Christie Over a year ago

Can you explain why it is better than using a reducer, please?

Nina Scholz Over a year ago

it is just a compact approachwithout creating objects over an over.

Collectives™ on Stack Overflow

What is the most efficient way to convert an array of objects to an object

3 Answers 3

Comments

Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related