how to get array from object with index as one of the object property

Question

I have an object

const items = {
  "123": {
    "key": 123,
    "name": "one name",
    },
    "456": {
    "key": 456,
    "name": "two name",
    },
    "789": {
    "key": 789,
    "name": "three name",
    },
    };

Need to filter this from below array, with array index as object.key

const myFilter = [123,789];

Code I am trying is as below but it returning array inedx as 0,1,2... but I need the index to be object.key.

let selectedItems = myFilter.map((key) => {
        return items[key];
      });

Current output :

[0:{
  key: 123,
  name: "one name"
}, 1: {
  key: 789,
  name: "three name"
}]

Expected Output

[123:{
  key: 123,
  name: "one name"
}, 789: {
  key: 789,
  name: "three name"
}]

jsfiddle - https://jsfiddle.net/kb374exh/2/

Your Expected output is not valid array, or even a object for that matter. — ikiK, Apr 30 '21 at 02:41
yup, and also your `items` variable is an object of object not array of object. so, you can't use array method for that — DSPdav, Apr 30 '21 at 02:45
Also, why ````123```` and ````789```` and no the ````456````? — AttemptedMastery, Apr 30 '21 at 02:47
@ikiK - I tried to edit the output format. Basically I need an array index to be the key property of the object and not 0,1,2...., sorry If Its confusing — codingHack, Apr 30 '21 at 03:12

Drew Reese · Answer 1 · 2021-04-30T04:32:14.093

Your actual output is actually correct and the only possible result from mapping the myFilter array to the matching properties from items.

const items = {
  "123": {
    "key": 123,
    "name": "one name",
  },
  "456": {
    "key": 456,
    "name": "two name",
  },
  "789": {
    "key": 789,
    "name": "three name",
  },
};

const myFilter = [123, 789];

const selectedItems = myFilter.map((key) => items[key]);

console.log(selectedItems);

The logged output you see is including the array index. You likely are seeing the index included when logging in the browser.

If you want an array of objects where the original key is the new index then the best you can likely do is an array of length <highest key> and a bunch of "holes" that are simply undefined.

const items = {
  "123": {
    "key": 123,
    "name": "one name",
  },
  "456": {
    "key": 456,
    "name": "two name",
  },
  "789": {
    "key": 789,
    "name": "three name",
  },
};

const myFilter = [123, 789];

const selectedItems = Object.entries(items).reduce((selectedItems, [key, value]) => {
  if (myFilter.includes(value.key)) selectedItems[key] = value;
  return selectedItems;
}, []);

console.log(selectedItems);

If you are ok with the result being an object then you can have more succinct output, you'll basically end up with back with an object with key-value pairs filtered out.

const items = {
  "123": {
    "key": 123,
    "name": "one name",
  },
  "456": {
    "key": 456,
    "name": "two name",
  },
  "789": {
    "key": 789,
    "name": "three name",
  },
};

const myFilter = [123, 789];

const selectedItems = Object.fromEntries(Object.entries(items).filter(([, value]) => myFilter.includes(value.key)));

console.log(selectedItems);

how to get array from object with index as one of the object property

1 Answers1