ES6 extract array filtering array of object with array of id

Question

I need to extract from carriers the code of the items present in active array:

const carriers = [
  { id: 0, code: "gls" },
  { id: 1, code: "tnt" },
  { id: 2, code: "fedex" },
  { id: 3, code: "ups" },
  { id: 4, code: "postnl" },
];
const active = [0, 2, 3];
const active_code = [];

let result = carriers.filter((c) => active.includes(Number(c.id)));
console.log(result);

result.forEach((item) => {
  active_code.push(item.code);
});
console.log(active_code);

Expected result:

["gls", "fedex", "ups"]

The above code works, but I'd like to learn if there's a better/easier/more elegant way to get the same result?

Thanks

Parvesh Kumar · Accepted Answer · 2021-09-06 01:36:09Z

1

As a starter a tweak can be done by mapping it instead of creating a blank array and pushing to it.

carriers.filter(i=>active.includes(+i.id)).map(i=>i.code)

answered Sep 6, 2021 at 1:36

Parvesh Kumar

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1 Comment

Joe Over a year ago

I think this is not the best solution, but, IMHO, it is the easiest to understand for who will facing the same issue with limited skills as I have

CertainPerformance · Accepted Answer · 2021-09-06 01:33:00Z

0

Map the active array by .finding the associated carrier.

const carriers = [
                  {"id":0,"code":"gls"},
                  {"id":1,"code":"tnt"},
                  {"id":2,"code":"fedex"}, 
                  {"id":3,"code":"ups"},
                  {"id":4,"code":"postnl"}
                 ];
const active = [0,2,3];

const result = active.map(id => carriers.find(c => c.id === id).code);
console.log(result);

For less computational complexity, turn the carriers into a structure indexed by ID first.

const carriers = [
                  {"id":0,"code":"gls"},
                  {"id":1,"code":"tnt"},
                  {"id":2,"code":"fedex"}, 
                  {"id":3,"code":"ups"},
                  {"id":4,"code":"postnl"}
                 ];
const active = [0,2,3];

const carriersById = Object.fromEntries(
  carriers.map(c => [c.id, c])
);
const result = active.map(id => carriersById[id].code);
console.log(result);

answered Sep 6, 2021 at 1:33

CertainPerformance

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1 Comment

navnath Over a year ago

both perfect solution

DecPK · Accepted Answer · 2021-09-06 02:07:02Z

1) You can achieve the result using Map.

const carriers = [
  { id: 0, code: "gls" },
  { id: 1, code: "tnt" },
  { id: 2, code: "fedex" },
  { id: 3, code: "ups" },
  { id: 4, code: "postnl" },
];
const active = [0, 2, 3];

const map = new Map(carriers.map(({ id, code }) => [id, code]));
const active_code = active.map((id) => map.get(id));

console.log(active_code);

2) You can also get the result using Set

const carriers = [
  { id: 0, code: "gls" },
  { id: 1, code: "tnt" },
  { id: 2, code: "fedex" },
  { id: 3, code: "ups" },
  { id: 4, code: "postnl" },
];
const active = [0, 2, 3];

const set = new Set(active);
const active_code = carriers
  .filter((o) => set.has(o.id))
  .map(({ code }) => code);

console.log(active_code);

Erlend · Accepted Answer · 2021-09-06 02:27:17Z

0

I would map the carriers data to active_code directly.

You could also create an active_ids object to avoid calling includes for every entry.

const carriers = [
    { "id": 0, "code": "gls" },
    { "id": 1, "code": "tnt" },
    { "id": 2, "code": "fedex" },
    { "id": 3, "code": "ups" },
    { "id": 4, "code": "postnl" }
];
const active = [0, 2, 3];

const active_ids = Object.fromEntries(active.map(i => [i, true]));

let active_code = carriers
    //.filter(c => active.includes(c.id))
    .filter(c => active_ids[c.id])         // faster if many items?
    .map(c => c.code)

console.log(active_code);

// expected ["gls", "fedex", "ups"]
console.assert(active_code[0] === "gls")
console.assert(active_code[1] === "fedex")
console.assert(active_code[2] === "ups")

edited Sep 6, 2021 at 2:27

answered Sep 6, 2021 at 2:05

Erlend

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