Create nested Object from an Array

Question

I have the following array of objects

const sorted = [
{
IsoCode: "EUR",
Buy: 1.948,
Sell: 1.963
},
{
IsoCode: "GBP",
Buy: 2.1184,
Sell: 2.1894
},
{
IsoCode: "USD",
Buy: 1.5781,
Sell: 1.6484
},
]

and I want to create an Object looking like this

    {
            USD: 
            {
              buy:1.5781,
              sell:1.6484,
    
            },
            EUR:
            {
              buy:1.948,
              sell:1.963,
            },
            GBP: 
            {
              buy:2.1184,
              sell:2.1894,
            }
          }

Currently I'am assigning the values manually, but I don't think this is scalable. I'm looking for more effective approach.

Have you tried a loop? Please post your current code as well. — Bergi
– Bergi, Commented Dec 8, 2020 at 17:07

trincot · Accepted Answer · 2020-12-08 17:11:53Z

3

I would go for Object.fromEntries and the object rest syntax:

const sorted = [{IsoCode: "EUR",Buy: 1.948,Sell: 1.963},{IsoCode: "GBP",Buy: 2.1184,Sell: 2.1894},{IsoCode: "USD",Buy: 1.5781,Sell: 1.6484},];

let res = Object.fromEntries(sorted.map(({IsoCode, ...rest}) => [IsoCode, rest]));

console.log(res);

answered Dec 8, 2020 at 17:11

trincot

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Comments

Guerric P · Accepted Answer · 2020-12-08 17:10:16Z

2

You could use Array.prototype.reduce() like this:

const sorted = [{
    IsoCode: "EUR",
    Buy: 1.948,
    Sell: 1.963
  }, {
    IsoCode: "GBP",
    Buy: 2.1184,
    Sell: 2.1894
  }, {
    IsoCode: "USD",
    Buy: 1.5781,
    Sell: 1.6484
  },
]

const obj = sorted.reduce(
  (acc, { IsoCode, Buy, Sell }) => 
    (acc[IsoCode] = { Buy, Sell }) && acc,
  {}
);

console.log(obj);

edited Dec 8, 2020 at 17:10

answered Dec 8, 2020 at 17:03

Guerric P

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5 Comments

Bergi Over a year ago

What's that IIFE good for? Also arr is not an array.

Guerric P Over a year ago

It's to extract needed properties

Bergi Over a year ago

But why not just destrucure the cur parameter to the reducer directly? (acc, {IsoCode, Buy, Sell}) => { acc[IsoCode] = {Buy, Sell}; return acc; }

adiga Over a year ago

Something like this might be better:sorted.reduce((acc, { IsoCode, ...rest }) => ({ ...acc, [IsoCode]: rest }),{})

Guerric P Over a year ago

It just depends whether OP wants to extract these exact keys or the rest, which is not precised. Also, having a pure function instead of mutating the accumulator is just one's opinion.

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