How to obtain values from Array in JS in an optimal way

July 25, 2022

I need to obtain a few values from a MAP in JS based on its id ("codi" in the object).

My array is something like this but bigger:

0: {codi: '291', literal: 'MEDIFIATC Progres 2010 ', check: true}
1: {codi: '292', literal: 'MEDIFIATC Progres < 2010 ', check: true}
2: {codi: '293', literal: 'MEDIFIATC Progres ', check: true}
3: {codi: '294', literal: 'MEDIFIATC Progres 2013  ', check: true}
4: {codi: '295', literal: 'MEDIFIATC Progres 2014 ', check: true}
5: {codi: '296', literal: 'MEDIFIATC MEDIFIATC  ', check: true}
6: {codi: '297', literal: 'MEDIFIATC MEDIFIATC P5 ', check: true}
7: {codi: '298', literal: 'MEDIFIATC MEDIFIATC P15 ', check: true}
8: {codi: '299', literal: 'MEDIFIATC MEDIFIATC DIAGONAL ', check: true}

Currently I am working on a simple loop, I iterate an when my variable is equals to the "codi" and return the entry.

function obtenerSubgrupo(codi) {
    for(j = 0; j < Object.keys(listaSubgrupo).length; j++) {
        if (codi == listaSubgrupo[i].codi) {
                return listaSubgrupo[i];
        }
    }   
}

How can I improve this?

I also need to extract the values that i am going to return from my main array, currently working with the info of: How can I remove a specific item from an array? but any help on that will be welcome too

Thanks.

EDIT: Just to put here the links shared by Simone Rossaini in the comments as i think they are quite useful:

https://javascript.plainenglish.io/are-for-loops-better-than-arrays-filter-or-foreach-methods-f54b6880d201

https://www.measurethat.net/Benchmarks/Show/4261/0/find-vs-forof-vs-for-loop

>Solution :

Assuming the codi values are unique convert the array to a Map or an object using the codi value as the key. It makes it simple to get at the data then.

This old question/set of answers re the value of which structure to use will be very helpful on deciding which to use.

Map:

const arr=[{codi:"291",literal:"MEDIFIATC Progres 2010 ",check:!0},{codi:"292",literal:"MEDIFIATC Progres < 2010 ",check:!0},{codi:"293",literal:"MEDIFIATC Progres ",check:!0},{codi:"294",literal:"MEDIFIATC Progres 2013  ",check:!0},{codi:"295",literal:"MEDIFIATC Progres 2014 ",check:!0},{codi:"296",literal:"MEDIFIATC MEDIFIATC  ",check:!0},{codi:"297",literal:"MEDIFIATC MEDIFIATC P5 ",check:!0},{codi:"298",literal:"MEDIFIATC MEDIFIATC P15 ",check:!0},{codi:"299",literal:"MEDIFIATC MEDIFIATC DIAGONAL ",check:!0}];

const map = new Map();

for (const obj of arr) {
  map.set(obj.codi, obj);
}

console.log(map.get('298'));

Object:

const arr=[{codi:"291",literal:"MEDIFIATC Progres 2010 ",check:!0},{codi:"292",literal:"MEDIFIATC Progres < 2010 ",check:!0},{codi:"293",literal:"MEDIFIATC Progres ",check:!0},{codi:"294",literal:"MEDIFIATC Progres 2013  ",check:!0},{codi:"295",literal:"MEDIFIATC Progres 2014 ",check:!0},{codi:"296",literal:"MEDIFIATC MEDIFIATC  ",check:!0},{codi:"297",literal:"MEDIFIATC MEDIFIATC P5 ",check:!0},{codi:"298",literal:"MEDIFIATC MEDIFIATC P15 ",check:!0},{codi:"299",literal:"MEDIFIATC MEDIFIATC DIAGONAL ",check:!0}];

const out = {};

for (const obj of arr) {
  out[obj.codi] = obj;
}

console.log(out['298']);